(via Gem & Jewellery News, Vol.7, No.1, December 1997) Harry Levy writes:
The ulcer that has been plaguing our trade has flared yet again. You will recall the recent story about the jeweler in the United States who sold filled diamonds without declaring the process to his customers. That story ended tragedy with the jeweler in question taking his own life. One must emphasize that the filling of diamonds is one of the few treatments that is recognized by all sections of the trade to be declarable.
Another case has now occurred in the USA, this time over the fissure filling of an emerald and again the retail purchaser was reportedly not told of the treatment. It is difficult to work out exactly what has happened in this case as the reports one reads in the trade press do not tell the same story. Briefly, as I understand it, an emerald was sold for $14000 and has ended up costing the seller nearly $400000 in compensation and fines.
The case occurred in Washington DC. An emerald ring was sold, and after several months was taken to a jeweler for some alterations and the emerald was damaged in the process. The jeweler informed the owner that the emerald had been filled with Opticon resin and heating had caused the damage. The original sellers claimed that the emerald they sold had not been so treated and if Opticon was now present it had not been put there by them and must have been introduced into the stone after they had sold it.
The owner sued the seller and others including the appraiser (the valuer) and the insurance company. The case was heard in front of a jury and in spite of trade testimony as to the present ambiguity about disclosure of resin filling of emeralds in the trade, the jury found in favor of the owner. The jeweler was found guilty on a number of counts including Breach of Warranties, Unlawful Trade Practice and Outrageous Trade Practice. The consumer was awarded treble damages in the amount of $78000 and, with legal costs, the total amounted to $400000. At the time of writing an appeal against judgments has been lodged.
Total disclosure?
Those who have advocated ‘total disclosure’ over the years can now say ‘We told you so’. Disclose everything and sleep at nights.
Unfortunately it is not that simple, as I have tried to point out in previous articles, because it is often difficult to detect some treatments. Stones have been treated from the time that they were first used as ornaments and objects of value. Oiling, waxing, bleaching, heating and burning are all treatments, and even cutting and polishing can be considered a treatment. And when one cuts and polishes for example an emerald, oil is used and if the stone has open fissures some of this oil will penetrate the stone.
When the trade began to organize itself through bodies such as CIBJO and the Diamond Bourses, they tried to lay down guidelines as to what treatments should be disclosed. Some treatments had long been applied to certain stones and those early legislators introduced the concept of ‘accepted trade practice.’ As new processes come about the trade initially tries to slot them in to the existing rules and if it cannot do this then new rules were made.
They try to use commonsense and look at other trades. They too have their ‘accepted trade practices.’ When you buy an article made of real leather you are not told that it has been treated, oiled, stained, stretched and has had other things done to it. Or when you buy a woolen article again the various treatments it has undergone are not enumerated.
Perhaps we should regard our trade as being sui generic, i.e. it is unique of its kind and cannot be compared to other trades. In this modern age, when consumer rights have become paramount, the trade should no longer hide behind ‘accepted trade practices’ and should tell the consumer everything they know. But this is where the problems start. The only person who knows for certain if a treatment has been applied to a stone is the person who actually carries out that treatment. If he does not disclose, or someone in the chain does not disclose, then to detect the disclosure becomes detective work and not everyone is capable of carrying out such detection.
Repeated oiling
Let us look at the specific case of the fissure filling of emeralds—this after all is one of the problems still not solved within the trade. Emeralds, from the time they are taken out of the ground, are constantly oiled. They are oiled after the rough has been cleaned, they are oiled while the rough remains unsold, they are oiled after cutting, they are oiled after polishing. In the way everyone knows that leather is oiled, dealers and jewelers have assumed that everyone knows emeralds are oiled. Like leather the oil dries out, but in contrast to leather the consumer expects the emerald to retain its beauty. Emeralds are oiled because they have open fissures (only rarely are emeralds free from open fissures) and any oil that goes in will eventually come again, as is the case with leather.
Over the past few years attempts have been made to keep the oil thus introduced in the emerald for as long as possible. This has been tried using different oils, and also pressure is used in some cases to ensure that the oil penetrates further into the stone and will thus evaporate more slowly. Attempts have also been made to seal the oil in the emerald. In recent years resins are being used, especially ones with refractive indices similar to natural emerald to make them less visible. The most popular resin that was eventually used was a synthetic one marketed under the name Opticon. This was already being used in the building trade to cover the cracks and fissures in marble and other decorative stones. But since this was still a volatile substance, albeit with low volatility they tried to seal it into the stone. It was found that it reacted with a hardening substance and solidified. At first this was done with all Opticon when it was introduced into the emerald. When it dried it solidified, but in some stones it contracted and gaps appeared inside the stone which gave rise to a rainbow effect and made the appearance worse than the untreated stones. Some fillings also discolored in time, again spoiling the appearance of the stone. Some techniques involved introduction of the resin under pressure causing the stone to be in tension and liable to shatter if any pressure was applied.
Hardening substance
To overcome these problems the Opticon was introduced into the stone and the hardening substance was applied to the surface only. Thus the theory was that this would seal in the filler without incurring the problems encountered above. But again it was found that tension could remain in the stone rendering it more fragile than untreated stones. So in many cases now the Opticon is introduced into the stone in the way that oil was used in the old days without the use of any hardening material. The trade does not like to use the word Opticon, as this is a trade name and other similar resins may be used. So the term now used is resin filled and the resin may be natural or artificial, i.e. man-made.
The traditionalists wanted to differentiate between oils that they had used and the new resins now being used. It is difficult to find a rationale for such thoughts. Perhaps they wished to protect their old stocks, perhaps they were scared of change, but there was a clamor within the trade, but not by the public, to differentiate between oils and resins. Many more gem quality stones can have their appearance improved with resins than with traditional oils, which was perhaps the reason for a sudden increase in the number of such stones on the market.
Raman spectroscopy
The situation at present is that many people in the trade regard the fissure filling of an emerald with a resin to be inferior to that of an oil and refuse to buy resin-filled stones. The demand was made on the laboratories to make this differentiation, and most labs claimed they could do so. But then came the claim by some laboratories that with the use of Raman spectroscope they could now positively identify the filling materials. Such a claim implies that without the use of such a instrument, the detection of the filler to be a resin as opposed to an oil was, in many cases, more guesswork than knowledge.
How does the Raman spectroscope work? In Rapaport Diamond Report (20 (38)) it is made clear that even the use of this latest technology is not foolproof. Briefly a laser beam of light is pointed at the filler and the resulting spectra are compared with those of known substances. A stone may undergo several treatments with different substances and the Raman analysis will only give a result for the one spot on which the beam has been focused, which is minute. So, many spots would have to be examined to give a more complete answer. Such an instrument costs about $200000 so many laboratories cannot afford such an expense.
What is the answer?
Where does the answer lie to such a problem? The trade is beginning to realize the answer should come through education and not merely legislation. The education must be effective in the High Street shops, for it is the retailer who is in the front line. And it is the sales person who is obliged in law to sell correctly described goods—which means to a certain extent educating the customer.
Many dealers now feel that filling a stone with a resin is no different to filling a stone with an oil. If a hardener is used the situation is of course different. Information is transmitted down the line by the use of general disclosure that stones have fissures filled to improve their clarity and others, such as corundum, are heated to improve their color and sometimes clarity. This is the best that the trade has come up with at present.
How will all this stand up in a court here? I am no lawyer but I suspect that the judge will listen to the trade practice if the dispute is within the trade, but may apply other standards if a member of the general public claims that they have been cheated.
Wednesday, May 02, 2007
Hot Gems And Fake Diamonds
(via Gem & Jewellery News, Vol. 7, Number 2, March 1998) Harry Levy writes:
1998 started with an international alarm for the gem trade and jewelry markets. The scare began in Bangkok with news that quantities of radioactive chrysoberyl cat’s eyes were being sold there and exported all over the world.
A few gem species have been irradiated for a number of years now to improve or change their color. The stone most subjected to this treatment has been white topaz. The most common types of irradiation have been electron and neutron bombardment of the stones to produce various shades of blue.
Electron irradiation produces paler shades of blue, known in the trade as ‘sky blue’. In this instance rough or cut pieces of white topaz are exposed to electron irradiation and the longer the exposure the stronger is the color, but a saturation point is reached beyond which the color will not intensify. When the stones are annealed (heated and maintained at certain temperatures) they turn blue. On cooling the stones maintain their color and the color change is permanent as far as we know.
The dealer or cutter who has the stones irradiated determines the amount of radiation the stones should be exposed to; this is an economic decision, as the longer the stones are irradiated the higher is the cost charged by the laboratory. Different stones from different localities need different quantities of irradiation to obtain the optimum color, but the dealer cannot experiment with small quantities as the fee for irradiation is based on the time and strength of exposure for material in a chamber of fixed capacity, however full it is. The other popular method is to expose the stones to neutron irradiation and in this instance the blue color produced is known in the trade as ‘London blue’. The color known as ‘Swiss blue’ is obtained by applying both types of irradiation to the topazes.
Since the color changes produced in topaz have been so dramatic, other stones have been exposed to such treatments in the hope of producing similar changes and this has resulted in such stones as ‘hot pink’ tourmalines (the hotness referring to the color not the radioactivity), and various colors in diamonds.
Subjecting a stone to irradiation is not something that can be done in the back of a kitchen or in a shed at the bottom of the garden. Stones are irradiated in a nuclear accelerator at known nuclear plants, research institutions or universities. Normally they are subject to the most rigorous government controls and workers would never release material which was dangerously radioactive to anyone involved in the gem trade. The stones are only released from such establishments when they display acceptable levels of radioactivity.
Scares about radioactive gemstones have been circulating ever since it became known that they could be treated in this manner. We are all exposed to various levels of irradiation in our everyday lives. During one of the early discussions it was alleged that a single flight in Concorde exposed one to more radiation, due to the height of the flight path, than being covered in irradiated topaz for a lifetime.
Other scare stories have concerned irradiated topaz being stolen from various vaults in Brazil, where they had been put to cool, and sold on the international markets while they were still dangerously radioactive. A similar story emerged at one of the Hong Kong shows about such stones from China. The basis for such stories seems to be economic, where dealers from one center are more than keen to believe that stones coming cheaper from another source must be dangerous.
Dealers and others who handle such stones would never expose themselves, their families, their staff or their customers to such danger, although with rumors constantly circulating in the trade an increasing number of dealers are beginning to include an instrument for detecting radioactivity as part of their equipment. A simple Geiger counter registers most but not all the known rays that could be present, other instruments are needed to register the troublesome ones.
Coming back to our radioactive chysoberyls, the media picked up the story and television pictures were flashed round the world showing worried-looking dealers and jewelry shop owners in Bangkok being shown such stones next to ticking Geiger counters. This is a marvelous story for an investigative reporter and whole television programmes on this topic have been shown in such countries as Germany.
Unless the trade is very careful, a lay person watch such a programme will be told about radioactive chrysoberyl cat’s eyes, but will only remember radioactivity in association with gemstones in general, and continued media coverage will soon convince him and his ilk that every stone and every diamond is radioactive and hence all jewelry is dangerous to wear.
Of course, the public has rarely proved itself to be so fickle. They are aware that many things they come into contact with have been subjected to irradiation, but they trust the authorities and the traders to be responsible and not subject them to any danger. It again comes down to education and all those involved in the jewelry trade must make themselves aware of exactly what they are handling. It is not enough to have the ability to buy and sell something at a profit, because the trade should be the ones most able to educate the public, who are their customers, answer their questions and allay any fears they may come across. And the safest way to trade is to deal with reputable suppliers.
1998 started with an international alarm for the gem trade and jewelry markets. The scare began in Bangkok with news that quantities of radioactive chrysoberyl cat’s eyes were being sold there and exported all over the world.
A few gem species have been irradiated for a number of years now to improve or change their color. The stone most subjected to this treatment has been white topaz. The most common types of irradiation have been electron and neutron bombardment of the stones to produce various shades of blue.
Electron irradiation produces paler shades of blue, known in the trade as ‘sky blue’. In this instance rough or cut pieces of white topaz are exposed to electron irradiation and the longer the exposure the stronger is the color, but a saturation point is reached beyond which the color will not intensify. When the stones are annealed (heated and maintained at certain temperatures) they turn blue. On cooling the stones maintain their color and the color change is permanent as far as we know.
The dealer or cutter who has the stones irradiated determines the amount of radiation the stones should be exposed to; this is an economic decision, as the longer the stones are irradiated the higher is the cost charged by the laboratory. Different stones from different localities need different quantities of irradiation to obtain the optimum color, but the dealer cannot experiment with small quantities as the fee for irradiation is based on the time and strength of exposure for material in a chamber of fixed capacity, however full it is. The other popular method is to expose the stones to neutron irradiation and in this instance the blue color produced is known in the trade as ‘London blue’. The color known as ‘Swiss blue’ is obtained by applying both types of irradiation to the topazes.
Since the color changes produced in topaz have been so dramatic, other stones have been exposed to such treatments in the hope of producing similar changes and this has resulted in such stones as ‘hot pink’ tourmalines (the hotness referring to the color not the radioactivity), and various colors in diamonds.
Subjecting a stone to irradiation is not something that can be done in the back of a kitchen or in a shed at the bottom of the garden. Stones are irradiated in a nuclear accelerator at known nuclear plants, research institutions or universities. Normally they are subject to the most rigorous government controls and workers would never release material which was dangerously radioactive to anyone involved in the gem trade. The stones are only released from such establishments when they display acceptable levels of radioactivity.
Scares about radioactive gemstones have been circulating ever since it became known that they could be treated in this manner. We are all exposed to various levels of irradiation in our everyday lives. During one of the early discussions it was alleged that a single flight in Concorde exposed one to more radiation, due to the height of the flight path, than being covered in irradiated topaz for a lifetime.
Other scare stories have concerned irradiated topaz being stolen from various vaults in Brazil, where they had been put to cool, and sold on the international markets while they were still dangerously radioactive. A similar story emerged at one of the Hong Kong shows about such stones from China. The basis for such stories seems to be economic, where dealers from one center are more than keen to believe that stones coming cheaper from another source must be dangerous.
Dealers and others who handle such stones would never expose themselves, their families, their staff or their customers to such danger, although with rumors constantly circulating in the trade an increasing number of dealers are beginning to include an instrument for detecting radioactivity as part of their equipment. A simple Geiger counter registers most but not all the known rays that could be present, other instruments are needed to register the troublesome ones.
Coming back to our radioactive chysoberyls, the media picked up the story and television pictures were flashed round the world showing worried-looking dealers and jewelry shop owners in Bangkok being shown such stones next to ticking Geiger counters. This is a marvelous story for an investigative reporter and whole television programmes on this topic have been shown in such countries as Germany.
Unless the trade is very careful, a lay person watch such a programme will be told about radioactive chrysoberyl cat’s eyes, but will only remember radioactivity in association with gemstones in general, and continued media coverage will soon convince him and his ilk that every stone and every diamond is radioactive and hence all jewelry is dangerous to wear.
Of course, the public has rarely proved itself to be so fickle. They are aware that many things they come into contact with have been subjected to irradiation, but they trust the authorities and the traders to be responsible and not subject them to any danger. It again comes down to education and all those involved in the jewelry trade must make themselves aware of exactly what they are handling. It is not enough to have the ability to buy and sell something at a profit, because the trade should be the ones most able to educate the public, who are their customers, answer their questions and allay any fears they may come across. And the safest way to trade is to deal with reputable suppliers.
How Can The Independent Jeweller Compete?
(via Gems & Jewellery News, Vol. 8, Number 1, December 1998) Harry Levy writes:
By the time you read this article the Christmas season will be behind us. At the time of writing it is difficult to predict what sort of Christmas our trade will have this year. The patterns of yesteryear have long since left us. In those days, by the end of October most outlets had placed their orders for Christmas and, apart from a few specials at the last minute, we all knew what sort of year we would have. As far as the independent jeweler is concerned today, most of his sales will consist of specials, and he will leave his orders up to the last minute, as will his customers.
So rather than sit and take stock as to what has happened this year let us try to look to the future, to next year and beyond.
Alternative outlets
The jewelry trade has fragmented and the loser has been the traditional high street jewelry shop. He has seen his business go to the multinationals, mail order catalogues, and now mail order shops, TV outlets and soon the Internet, although this is with us already, as well as the auction houses. How much business these new outlets have actually taken away, as opposed to creating new demands and bringing in different sections of the public to buy jewelry items is debatable.
I recall many years ago when I first set up home, I needed some fitted carpets. I had a cousin in the trade who promised me that he would supply me the carpets. I bought from him and it was only several weeks later, when I was in one of the specialist carpet stores with branches everywhere, that I saw my identical carpet at prices above twenty percent below what I had paid my cousin. On complaining to him, he informed me that the groups had a much higher buying power than him and thus could negotiate better prices than he could get.
We have a similar situation in our trade at present. Many jewelers have remarked that they cannot make an article for the price that the same thing can be bought from these outlets. How can they compete?
The simple answer is that they cannot. So in order to survive they must concentrate on selling articles which the outlets cannot make. Put very simply, it means that they must try to sell jewelry which cannot be readily duplicated.
Mass production
The mass market depends on selling numbers of identical units. A piece of jewelry is selected by a buyer or a panel to go into their range. In almost all cases the buyers are not jewelry specialists and in order to ensure that they get and sell pieces that match up to their original samples, they insist on each item being exactly the same for any given line. Thus, if one is selling an amethyst and diamond cluster ring, the diamonds must all be of a similar size and quality and the amethysts, likewise, must all be identical. It is not enough that they be of the same size and shape, but must all be of the same hue in color and purity.
The manufacturer who supplies these articles must set up to produce identical units and periodically to reduce his prices in order to stay in with the buying group. He can do this by improving his manufacturing processes and reducing the price of his components, as well as reducing his profits.
Falling standards
Several years ago, one of the manufacturers who were supplying one of the multiples stopped buying a type of stone for which he had given me regular orders. When I asked him why he had stopped ordering these stones from me and accused him of buying them elsewhere, he remarked that the group was constantly asking him to reduce his price. The article was a pair of earrings, and the only way left for him to reduce the price was to make the gold thinner and thinner, until he reached the situation where there was not enough gold to hold the stones in place so they kept dropping out. In the end he dropped the line.
The manufacturers in this country try to source their components, and eventually find that the article can be produced and purchased much more cheaply abroad. Finally they become importers and put the finishing touches in this country as part of their manufacturing process. With the prospect of hallmarking being no longer mandatory in this country, they will become merely re-packers of such items. They also run the risk that their customers, in turn, will use outlets abroad and cut them out totally. Luckily for us, many of these items produced abroad do not have the quality of those that are made in this country and hopefully the buyers will appreciate this fact and return to rely on home produced goods.
I see little future for those of us who are middle people in our trade. The large groups will find ways of marketing the goods to the public, and sourcing them, cutting out our retailers and manufacturers. Their main criterion will be price and while it remains that way quality will suffer.
The way forward
Quality is the factor on which our own trade will survive, producing jewelry that is good in quality and value for money. Such jewelry must be sold on the rarity of its components and the craftsmanship of its makers. There will always be a place for the High Street Jeweler, even if he has to move into a mall and be right next to his competitors, provided he can sell things which are not easily imitated.
I come across many young and new designers and they are all finding outlets for the unique pieces of jewelry they produce. The mass of cheap jewelry available now is making the public more aware of jewelry: they buy these items to wear a few times and then throw away. Let us hope that this awareness they are getting will make them want something a little better and more lasting for that special occasion, and when they think of buying such an item they will come into a high street jeweler.
I hope you all have an enjoyable Christmas and that some of you will put pen to paper and let us have your views about our trade. It is going through a state of flux, both in marketing, as the movement of goods becomes easier and in the amount and variety of treatments of the natural and synthetic gems that go into the making of a piece of jewelry.
By the time you read this article the Christmas season will be behind us. At the time of writing it is difficult to predict what sort of Christmas our trade will have this year. The patterns of yesteryear have long since left us. In those days, by the end of October most outlets had placed their orders for Christmas and, apart from a few specials at the last minute, we all knew what sort of year we would have. As far as the independent jeweler is concerned today, most of his sales will consist of specials, and he will leave his orders up to the last minute, as will his customers.
So rather than sit and take stock as to what has happened this year let us try to look to the future, to next year and beyond.
Alternative outlets
The jewelry trade has fragmented and the loser has been the traditional high street jewelry shop. He has seen his business go to the multinationals, mail order catalogues, and now mail order shops, TV outlets and soon the Internet, although this is with us already, as well as the auction houses. How much business these new outlets have actually taken away, as opposed to creating new demands and bringing in different sections of the public to buy jewelry items is debatable.
I recall many years ago when I first set up home, I needed some fitted carpets. I had a cousin in the trade who promised me that he would supply me the carpets. I bought from him and it was only several weeks later, when I was in one of the specialist carpet stores with branches everywhere, that I saw my identical carpet at prices above twenty percent below what I had paid my cousin. On complaining to him, he informed me that the groups had a much higher buying power than him and thus could negotiate better prices than he could get.
We have a similar situation in our trade at present. Many jewelers have remarked that they cannot make an article for the price that the same thing can be bought from these outlets. How can they compete?
The simple answer is that they cannot. So in order to survive they must concentrate on selling articles which the outlets cannot make. Put very simply, it means that they must try to sell jewelry which cannot be readily duplicated.
Mass production
The mass market depends on selling numbers of identical units. A piece of jewelry is selected by a buyer or a panel to go into their range. In almost all cases the buyers are not jewelry specialists and in order to ensure that they get and sell pieces that match up to their original samples, they insist on each item being exactly the same for any given line. Thus, if one is selling an amethyst and diamond cluster ring, the diamonds must all be of a similar size and quality and the amethysts, likewise, must all be identical. It is not enough that they be of the same size and shape, but must all be of the same hue in color and purity.
The manufacturer who supplies these articles must set up to produce identical units and periodically to reduce his prices in order to stay in with the buying group. He can do this by improving his manufacturing processes and reducing the price of his components, as well as reducing his profits.
Falling standards
Several years ago, one of the manufacturers who were supplying one of the multiples stopped buying a type of stone for which he had given me regular orders. When I asked him why he had stopped ordering these stones from me and accused him of buying them elsewhere, he remarked that the group was constantly asking him to reduce his price. The article was a pair of earrings, and the only way left for him to reduce the price was to make the gold thinner and thinner, until he reached the situation where there was not enough gold to hold the stones in place so they kept dropping out. In the end he dropped the line.
The manufacturers in this country try to source their components, and eventually find that the article can be produced and purchased much more cheaply abroad. Finally they become importers and put the finishing touches in this country as part of their manufacturing process. With the prospect of hallmarking being no longer mandatory in this country, they will become merely re-packers of such items. They also run the risk that their customers, in turn, will use outlets abroad and cut them out totally. Luckily for us, many of these items produced abroad do not have the quality of those that are made in this country and hopefully the buyers will appreciate this fact and return to rely on home produced goods.
I see little future for those of us who are middle people in our trade. The large groups will find ways of marketing the goods to the public, and sourcing them, cutting out our retailers and manufacturers. Their main criterion will be price and while it remains that way quality will suffer.
The way forward
Quality is the factor on which our own trade will survive, producing jewelry that is good in quality and value for money. Such jewelry must be sold on the rarity of its components and the craftsmanship of its makers. There will always be a place for the High Street Jeweler, even if he has to move into a mall and be right next to his competitors, provided he can sell things which are not easily imitated.
I come across many young and new designers and they are all finding outlets for the unique pieces of jewelry they produce. The mass of cheap jewelry available now is making the public more aware of jewelry: they buy these items to wear a few times and then throw away. Let us hope that this awareness they are getting will make them want something a little better and more lasting for that special occasion, and when they think of buying such an item they will come into a high street jeweler.
I hope you all have an enjoyable Christmas and that some of you will put pen to paper and let us have your views about our trade. It is going through a state of flux, both in marketing, as the movement of goods becomes easier and in the amount and variety of treatments of the natural and synthetic gems that go into the making of a piece of jewelry.
Monday, April 30, 2007
The Tourist Trap Debate
(via Gem Market News, Jan/Feb 2007, Vol 26, Issue 1) Richard B Drucker, GG writes:
Every year, tourists purchase jewelry from port town shops, major city tourist areas, and even from cruise ships, either on board or at a recommended local store. The vacation is a great memory until they return home, only to be told by a local jeweler or appraiser that they have been ripped off. Are they really a victim of a devious tourist trap, or has the local jeweler or appraiser low-balled the value in an attempt to make a sale themselves or discredit the tourist industry?
The truth is that when tourists leave their home country, they are definitely at a disadvantage when shopping for any item, not just jewelry. Tourist stores know that they are dealing with clients with discretionary income and impulsive spending behavior when away from home. If they have a change of heart for any reason when they get home, exchanges or refunds are unlikely due to the difficulty related to the distance. There might be guarantees but once home, the guarantees may be hard to invoke. Since cruise lines often get commissions from jewelry stores they recommend, they may be helpful in assisting the passenger in a dispute. Credit card companies historically helped out and are good advice for tourists to use, however, they too, are becoming reluctant to help out because there are so many claims and few are warranted.
When there is a dispute, the consumer will probably be directed to get an independent appraisal and that is one reason that Gemworld sees so many of these purchases. In fairness to the tourist stores and cruise ships, we do see many cases where the purchase price is legitimate, so this is not just about the tourist trap.
Most of the time, when a client comes to us for the independent appraisal thinking they are overpaid, we substantiate the price paid. The problem starts when the jeweler says they overpaid and their store could sell it for less. Although they could sell it for less, this may also be an unfair statement. There are different markets to buy jewelry in and different markets have different pricing. Some markets get higher markups due to overhead, location, advertising, and yes, even the fact that they may be giving commissions to cruise operators. Someone can always sell something for less, but that is not what is at issue. The only thing that is important is whether the tourist received what they expected at a fair price for the location in which they made the purchase.
Appraising in the Appropriate Market
Appraising in the appropriate market means research and due diligence by the appraiser. It means finding out what similar items sell for in similar stores. In the Sept/Oct 2006 issue of GMN, an article on markets appeared by Joseph Tenhagen. In it he identifies 14 separate and stratified markets in which jewelry can be purchased. It is our opinion that the appraiser should identify the market and research prices accordingly. We always ask where an item was purchased and value accordingly.
Occasionally, there may be reason to appraise an item in a different market than the one in which it was purchased. In the tourist examples, one may use the argument that if the item were lost, it would not be replaced in the same market. Appraisers may ask the question, “Where would you most likely replace this item if it were lost?” Since the tourist is unlikely to hop aboard the plane and return to the place of purchase, nor would the insurance company go to that store either, could it be appraised for a lower value in a different market? The answer is maybe.
First, if it is trademarked or branded from that store or location, it may likely have to be replaced only by that store. Then, you could not transfer the appraisal to a generic local replacement center. The opportunity to use a different market for replacement comes from the fact that most replacement type insurance policies state that they have the right to replace at their cost or to settle for the price that they could actually buy the item for, then one would argue that a low value is always appropriate. However, this will be the case with most purchases from all retail markets, and I am not sure that is where appraising should go. No jeweler would ever make a fair profit if this started to happen.
Sometimes a discussion may ensue regarding replacement and the client may request a lower value for insurance. Without going into a full discussion here about the appraisal methodology and valuation science, I will simply say that if a lower value is used for any reason, that reason should be clearly stated on the appraisal report. Something such as this could be added: Client purchased item at XYZ Jewelers, St.Thomas, for $4000.00. Although a fair price for that location, replacement value here in local markets has been determined to be $3200.00 and that value is being used at the request of the client.
Now, I know that appraisers love to debate methodology and appraising. There are many that would disagree with the above statement and procedure. One subscriber/appraiser recently emailed us regarding problems with a Caribbean purchase. While the heart of the issue was in some false claims, we also discussed valuation methods. He wrote the following. “My position is that it really doesn’t matter what the seller or buyer think the appraisal value of any item should be. It is what the market says it is. The client and/or seller can have absolutely no influence on an ethical appraisal. And, as an appraiser, I can’t really have an opinion on whether the price paid was too high or too low. There is no mention in the purpose and function statements of the appraisal being intended as a purchase price justification. As such, there is really no reason to identify the purchase price or to justify either the seller’s or the buyer’s position in a transaction. As appraisers, we are not in the business of taking sides (not should we be).”
While there is truth to much of this, other issues are at hand here. His position is that nothing influences what he ultimately appraises an item for. He states that the market dictates price, but what market? Market activity dictates value. Market location is an important factor in examining this activity. Disparaging terms such as rip off, etc., should be avoided. Appraisers are no more immune from civil recourse stemming from interfering in the commerce of others than anyone else. A purchase price is a valid indicator of value. If a comparable can be purchased in a different market for less, this might be noted. However, do not allow this to suggest that the original price was an unfair price for the market the consumer chose to shop within.
Appraisals of jewelry purchased in tourist markets present a challenge in that the appraiser must reconcile the role of market influence on value. Often these assignments blend two distinct tasks. One is assigning an insurance replacement value to aid the client in obtaining insurance. In this case, the purchase price may not be a significant consideration because the issue becomes not what was paid, but what would be paid to make the client whole again in case of a loss. However, this should not be done in a way that dismisses the legitimacy of an established tourist market.
Another example clearly illustrates this with real estate. Suppose a real estate appraiser were appraising a house. The appraiser finds that the builder of the home has built this exact home in a different city in another part of the country and it sold there for a lower price. The appraiser uses this price stating that this is all it would cost to replace the home with this builder. While the materials may be the same, the market value varies with location. The house does not cost the same in all locations, yet the appraiser would never say to the client that they were ripped off by paying the higher price in the place in which they chose to buy.
When the Gloves Come off
While we have defended many cases as the independent arbitrator, these cases have strictly involved the question of price. A bigger problem in our opinion is the misinformation and use of reports that inflate the grading of gems being sold. The value may be OK for what is sold or it may be high. In both cases, we will not defend the sale.
Every year, tourists purchase jewelry from port town shops, major city tourist areas, and even from cruise ships, either on board or at a recommended local store. The vacation is a great memory until they return home, only to be told by a local jeweler or appraiser that they have been ripped off. Are they really a victim of a devious tourist trap, or has the local jeweler or appraiser low-balled the value in an attempt to make a sale themselves or discredit the tourist industry?
The truth is that when tourists leave their home country, they are definitely at a disadvantage when shopping for any item, not just jewelry. Tourist stores know that they are dealing with clients with discretionary income and impulsive spending behavior when away from home. If they have a change of heart for any reason when they get home, exchanges or refunds are unlikely due to the difficulty related to the distance. There might be guarantees but once home, the guarantees may be hard to invoke. Since cruise lines often get commissions from jewelry stores they recommend, they may be helpful in assisting the passenger in a dispute. Credit card companies historically helped out and are good advice for tourists to use, however, they too, are becoming reluctant to help out because there are so many claims and few are warranted.
When there is a dispute, the consumer will probably be directed to get an independent appraisal and that is one reason that Gemworld sees so many of these purchases. In fairness to the tourist stores and cruise ships, we do see many cases where the purchase price is legitimate, so this is not just about the tourist trap.
Most of the time, when a client comes to us for the independent appraisal thinking they are overpaid, we substantiate the price paid. The problem starts when the jeweler says they overpaid and their store could sell it for less. Although they could sell it for less, this may also be an unfair statement. There are different markets to buy jewelry in and different markets have different pricing. Some markets get higher markups due to overhead, location, advertising, and yes, even the fact that they may be giving commissions to cruise operators. Someone can always sell something for less, but that is not what is at issue. The only thing that is important is whether the tourist received what they expected at a fair price for the location in which they made the purchase.
Appraising in the Appropriate Market
Appraising in the appropriate market means research and due diligence by the appraiser. It means finding out what similar items sell for in similar stores. In the Sept/Oct 2006 issue of GMN, an article on markets appeared by Joseph Tenhagen. In it he identifies 14 separate and stratified markets in which jewelry can be purchased. It is our opinion that the appraiser should identify the market and research prices accordingly. We always ask where an item was purchased and value accordingly.
Occasionally, there may be reason to appraise an item in a different market than the one in which it was purchased. In the tourist examples, one may use the argument that if the item were lost, it would not be replaced in the same market. Appraisers may ask the question, “Where would you most likely replace this item if it were lost?” Since the tourist is unlikely to hop aboard the plane and return to the place of purchase, nor would the insurance company go to that store either, could it be appraised for a lower value in a different market? The answer is maybe.
First, if it is trademarked or branded from that store or location, it may likely have to be replaced only by that store. Then, you could not transfer the appraisal to a generic local replacement center. The opportunity to use a different market for replacement comes from the fact that most replacement type insurance policies state that they have the right to replace at their cost or to settle for the price that they could actually buy the item for, then one would argue that a low value is always appropriate. However, this will be the case with most purchases from all retail markets, and I am not sure that is where appraising should go. No jeweler would ever make a fair profit if this started to happen.
Sometimes a discussion may ensue regarding replacement and the client may request a lower value for insurance. Without going into a full discussion here about the appraisal methodology and valuation science, I will simply say that if a lower value is used for any reason, that reason should be clearly stated on the appraisal report. Something such as this could be added: Client purchased item at XYZ Jewelers, St.Thomas, for $4000.00. Although a fair price for that location, replacement value here in local markets has been determined to be $3200.00 and that value is being used at the request of the client.
Now, I know that appraisers love to debate methodology and appraising. There are many that would disagree with the above statement and procedure. One subscriber/appraiser recently emailed us regarding problems with a Caribbean purchase. While the heart of the issue was in some false claims, we also discussed valuation methods. He wrote the following. “My position is that it really doesn’t matter what the seller or buyer think the appraisal value of any item should be. It is what the market says it is. The client and/or seller can have absolutely no influence on an ethical appraisal. And, as an appraiser, I can’t really have an opinion on whether the price paid was too high or too low. There is no mention in the purpose and function statements of the appraisal being intended as a purchase price justification. As such, there is really no reason to identify the purchase price or to justify either the seller’s or the buyer’s position in a transaction. As appraisers, we are not in the business of taking sides (not should we be).”
While there is truth to much of this, other issues are at hand here. His position is that nothing influences what he ultimately appraises an item for. He states that the market dictates price, but what market? Market activity dictates value. Market location is an important factor in examining this activity. Disparaging terms such as rip off, etc., should be avoided. Appraisers are no more immune from civil recourse stemming from interfering in the commerce of others than anyone else. A purchase price is a valid indicator of value. If a comparable can be purchased in a different market for less, this might be noted. However, do not allow this to suggest that the original price was an unfair price for the market the consumer chose to shop within.
Appraisals of jewelry purchased in tourist markets present a challenge in that the appraiser must reconcile the role of market influence on value. Often these assignments blend two distinct tasks. One is assigning an insurance replacement value to aid the client in obtaining insurance. In this case, the purchase price may not be a significant consideration because the issue becomes not what was paid, but what would be paid to make the client whole again in case of a loss. However, this should not be done in a way that dismisses the legitimacy of an established tourist market.
Another example clearly illustrates this with real estate. Suppose a real estate appraiser were appraising a house. The appraiser finds that the builder of the home has built this exact home in a different city in another part of the country and it sold there for a lower price. The appraiser uses this price stating that this is all it would cost to replace the home with this builder. While the materials may be the same, the market value varies with location. The house does not cost the same in all locations, yet the appraiser would never say to the client that they were ripped off by paying the higher price in the place in which they chose to buy.
When the Gloves Come off
While we have defended many cases as the independent arbitrator, these cases have strictly involved the question of price. A bigger problem in our opinion is the misinformation and use of reports that inflate the grading of gems being sold. The value may be OK for what is sold or it may be high. In both cases, we will not defend the sale.
Origin Determination Of Rubies, Sapphires And Emeralds
The lecture was delivered on the 8th December, 2004 at AIGS by Dietmar Schwarz and Christian Dunaigre, Gubelin Gem Lab, Switzerland.
In brief:
Historical data: The concept of country of origin determination started 60+ years ago in Switzerland by Dr. Eduard Gubelin who did methodical studies on internal features of gemstones originating from important gem localities around the world. During 1950s and 1970s the number of important gem deposits were restricted due to political and economic reasons. Some of the major deposits include:
Ruby: Ratnapura/Elahera in Sri Lanka
Mogok Stone Tract / Mong Hshu / Namya in Burma
Trat province in Thailand
Magari / Umba valley in East Africa
Different localities in Vietnam
Different localities in Madagascar
Sapphires: Ratnapura / Elahera in Sri Lanka
Mogok Stone Tract in Burma
Kanchanaburi / Chantaburi in Thailand
Different localities in Australia
Different localities in Madagascar
Different localities in the USA
Emeralds: Muzo / Chivor in Colombia
Different localities in Zambia
Sandawana in Zimbabwe
Ural mountains in Russia
Different localities in Brazil
Different localities in Afghanistan
Different localities in Pakistan
In today’s gem market, traders like to submit a ruby, sapphire or emerald for origin determination due to its high value. Inclusions do affect prices. There are number of reasons why inclusions alone are unreliable for determining the origin of gemstones. The current gemological knowledge of inclusions for various ruby + sapphire + emerald + other important colored stone occurrences are incomplete. Study of inclusions is a relatively new science and there is so much that remains to be learned + so many inclusions that have yet to be identified and catalogued. The key areas to be studied are:
- variation of the inclusion parameters within samples from a given locality
- similarity of inclusion populations in samples from different localities
- what sort of diagnostic origin information can we collect from a cut gemstone
- limitations in the determination of origin
- chemical fingerprinting
- advanced instruments such as UV, VIS-NIR, FTIR, Raman +++
During the 80s and 90s many new gem deposits were discovered. It was found that the mineralogical-gemological properties of the new sources were quite similar or even identical to those observed from the traditional sources. For instance blue sapphires from Madagascar displayed features that resembled sapphires from Sri Lanka, East Africa, Burma or even Kashmir. At the same time gemstones even when found in similar geological environments still showed some locality-specific features which allowed a clear separation from gems originating from a deposit of the same generic type such rubies from the Mogok and Mong Hshu.
Today gemological laboratories dealing with origin determination of colored stones are confronted with the gem production of an increasing number of mining areas all over the world. Some of the traditional sources are not producing gems consistently. Without any doubt the island of Madagascar has enormous potential for almost all gemstone species located in different regions of the country and related to different types of host rocks. Advanced + proprietary treatment techniques in rubies, sapphires and emerald may result in the elimination of characteristic features and make origin determination more difficult.
In brief:
Historical data: The concept of country of origin determination started 60+ years ago in Switzerland by Dr. Eduard Gubelin who did methodical studies on internal features of gemstones originating from important gem localities around the world. During 1950s and 1970s the number of important gem deposits were restricted due to political and economic reasons. Some of the major deposits include:
Ruby: Ratnapura/Elahera in Sri Lanka
Mogok Stone Tract / Mong Hshu / Namya in Burma
Trat province in Thailand
Magari / Umba valley in East Africa
Different localities in Vietnam
Different localities in Madagascar
Sapphires: Ratnapura / Elahera in Sri Lanka
Mogok Stone Tract in Burma
Kanchanaburi / Chantaburi in Thailand
Different localities in Australia
Different localities in Madagascar
Different localities in the USA
Emeralds: Muzo / Chivor in Colombia
Different localities in Zambia
Sandawana in Zimbabwe
Ural mountains in Russia
Different localities in Brazil
Different localities in Afghanistan
Different localities in Pakistan
In today’s gem market, traders like to submit a ruby, sapphire or emerald for origin determination due to its high value. Inclusions do affect prices. There are number of reasons why inclusions alone are unreliable for determining the origin of gemstones. The current gemological knowledge of inclusions for various ruby + sapphire + emerald + other important colored stone occurrences are incomplete. Study of inclusions is a relatively new science and there is so much that remains to be learned + so many inclusions that have yet to be identified and catalogued. The key areas to be studied are:
- variation of the inclusion parameters within samples from a given locality
- similarity of inclusion populations in samples from different localities
- what sort of diagnostic origin information can we collect from a cut gemstone
- limitations in the determination of origin
- chemical fingerprinting
- advanced instruments such as UV, VIS-NIR, FTIR, Raman +++
During the 80s and 90s many new gem deposits were discovered. It was found that the mineralogical-gemological properties of the new sources were quite similar or even identical to those observed from the traditional sources. For instance blue sapphires from Madagascar displayed features that resembled sapphires from Sri Lanka, East Africa, Burma or even Kashmir. At the same time gemstones even when found in similar geological environments still showed some locality-specific features which allowed a clear separation from gems originating from a deposit of the same generic type such rubies from the Mogok and Mong Hshu.
Today gemological laboratories dealing with origin determination of colored stones are confronted with the gem production of an increasing number of mining areas all over the world. Some of the traditional sources are not producing gems consistently. Without any doubt the island of Madagascar has enormous potential for almost all gemstone species located in different regions of the country and related to different types of host rocks. Advanced + proprietary treatment techniques in rubies, sapphires and emerald may result in the elimination of characteristic features and make origin determination more difficult.
Friday, April 27, 2007
Kashmir sapphire
On April 25, Christies auction house also set a record for the highest per carat price ever paid for a cushion cut 22.66 carat Kashmir sapphire, which was sold to an anonymous buyer for $3.064 million.
Useful link:
www.christies.com
Useful link:
www.christies.com
Baroda Pearls
Christies auction house sold a two strand natural pearl necklace with matching earrings, brooch and ring to a private Asian buyer for $7.096 million. The necklace features 68 of the finest and largest pearls from the seven strand natural pearl necklace that once belonged to The Royal Treasury of the Maharaja of Baroda.
Useful link:
www.christies.com
Useful link:
www.christies.com
Sapphire With Yellowish Orange Surface Coating
(via ICA Early Warning Flash, No.46, August 16, 1991) GIA GTL writes:
Description
The stone is a transparent oval mixed cut weighing 0.98 carat and measuring 6.80x4.90x3.36mm. It is medium yellowish orange in color which to the unaided eye appears uniform in distribution.
Gemological properties
Standard gemological testing identify the stone as a natural corundum. It exhibits no distinct absorption features when examined with a desk-model spectroscope and is inert to both long and short wave ultraviolet radiation. Interestingly, it exhibits no pleochroism when viewed through a calcite dichroscope, something that would be expected in a corundum of this hue and depth of color.
Magnification
Diffused transmitted lighting reveals that the stone has been surface coated. Irregularities in the coating—scratches and pits on pavilion facets as well as abrasions on facet junctions---indicate that this is an essentially colorless stone. Examination in surface reflected lighting reveals a predominantly purple iridescence on pavilion facets.
Additional testing
The ultraviolet visible absorption spectrum was found to be similar to that of natural color yellow sapphire with features related to Fe3+. A qualitative chemical analysis performed by EDXRF reveals the presence of iron as the dominating trace element, with small amounts of potassium, calcium, titanium and gallium. Neither ultraviolet visible absorption spectroscopy nor X-ray fluorescence helped to detect or characterize the coating.
Discussion
The microscope features of this stone show it to have been coated, with the coating being responsible for both the apparent body color and superficial iridescence. It is important to note that this is a surface coating and not a diffusion treatment.
‘Aqua Aura’ is the trade name used for a type of coated gem seen for some time now. This consists of such materials as unfashioned rock crystal specimen as well as faceted rock crystal and colorless topaz to which a thin layer of gold has been applied. The treatment produces a greenish blue apparent body color (the transmission color of the gold coating) and superficial iridescence. Treated gems of these type exhibit microscopic features like those described above. It is possible that the corundum described herein has been subjected to a similar coating but of a different substance.
Description
The stone is a transparent oval mixed cut weighing 0.98 carat and measuring 6.80x4.90x3.36mm. It is medium yellowish orange in color which to the unaided eye appears uniform in distribution.
Gemological properties
Standard gemological testing identify the stone as a natural corundum. It exhibits no distinct absorption features when examined with a desk-model spectroscope and is inert to both long and short wave ultraviolet radiation. Interestingly, it exhibits no pleochroism when viewed through a calcite dichroscope, something that would be expected in a corundum of this hue and depth of color.
Magnification
Diffused transmitted lighting reveals that the stone has been surface coated. Irregularities in the coating—scratches and pits on pavilion facets as well as abrasions on facet junctions---indicate that this is an essentially colorless stone. Examination in surface reflected lighting reveals a predominantly purple iridescence on pavilion facets.
Additional testing
The ultraviolet visible absorption spectrum was found to be similar to that of natural color yellow sapphire with features related to Fe3+. A qualitative chemical analysis performed by EDXRF reveals the presence of iron as the dominating trace element, with small amounts of potassium, calcium, titanium and gallium. Neither ultraviolet visible absorption spectroscopy nor X-ray fluorescence helped to detect or characterize the coating.
Discussion
The microscope features of this stone show it to have been coated, with the coating being responsible for both the apparent body color and superficial iridescence. It is important to note that this is a surface coating and not a diffusion treatment.
‘Aqua Aura’ is the trade name used for a type of coated gem seen for some time now. This consists of such materials as unfashioned rock crystal specimen as well as faceted rock crystal and colorless topaz to which a thin layer of gold has been applied. The treatment produces a greenish blue apparent body color (the transmission color of the gold coating) and superficial iridescence. Treated gems of these type exhibit microscopic features like those described above. It is possible that the corundum described herein has been subjected to a similar coating but of a different substance.
Wednesday, April 25, 2007
Dyed Natural Corundum As A Ruby Imitation
(via ICA Early Warning Flash, No.50, December 11, 1991) SSEF writes:
The following observations were made in the SSEF laboratory and further during examination of stones by Dr K Schmetzer and Mr F J Schupp, Germany.
Submitted stone chains and faceted stones were consisting of a heavily fractured type of natural corundum material, probably stained during quench cracking. They were sold as originating from India. The flattened beads were up to 15mm in diameter, the faceted oval stones between 5 and 8 carats.
Closer examination under the microscope reveals that the red color is deposited on irregular fracture planes only. The material is colored by a violetish red stain, the result of an artificial fracture treatment. The color is similar to the color of somewhat dark ruby and makes a convincing ruby imitation.
The stones show natural inclusions which consist of sets of parallel twin lamellae in one or two directions, forming straight intersection lines. Boehmite particles are confined to these intersection lines. Small double refractive mineral inclusions forming clusters were also observed. Stones with similar properties are known by us to come from East Africa. In immersion, light yellow or greenish yellow portions are forming areas between the fractures, showing the original color of the material. The red color is only seen in fractures. In thick pieces, the artificial treatment (i.e the stained fractures) is more difficult to see.
Beside of the above, the treated material can be recognized by a yellow fluorescence under long wave UV radiation. The red artificial color is said to fade after exposure of some weeks to daylight. Also the rather uneven color distribution on the fractures, as seen under magnification, is diagnostic.
The chromophore element of ruby is chromium. The easiest way to prove its presence in corundum is by observing the absorption spectrum with a pocket spectroscope. Chromium causes a prominent set of absorption lines and a fluorescence doublet in the red part of the spectrum. These characteristics are not visible in the dyed corundum since they lack chromium and therefore are not ruby.
The following observations were made in the SSEF laboratory and further during examination of stones by Dr K Schmetzer and Mr F J Schupp, Germany.
Submitted stone chains and faceted stones were consisting of a heavily fractured type of natural corundum material, probably stained during quench cracking. They were sold as originating from India. The flattened beads were up to 15mm in diameter, the faceted oval stones between 5 and 8 carats.
Closer examination under the microscope reveals that the red color is deposited on irregular fracture planes only. The material is colored by a violetish red stain, the result of an artificial fracture treatment. The color is similar to the color of somewhat dark ruby and makes a convincing ruby imitation.
The stones show natural inclusions which consist of sets of parallel twin lamellae in one or two directions, forming straight intersection lines. Boehmite particles are confined to these intersection lines. Small double refractive mineral inclusions forming clusters were also observed. Stones with similar properties are known by us to come from East Africa. In immersion, light yellow or greenish yellow portions are forming areas between the fractures, showing the original color of the material. The red color is only seen in fractures. In thick pieces, the artificial treatment (i.e the stained fractures) is more difficult to see.
Beside of the above, the treated material can be recognized by a yellow fluorescence under long wave UV radiation. The red artificial color is said to fade after exposure of some weeks to daylight. Also the rather uneven color distribution on the fractures, as seen under magnification, is diagnostic.
The chromophore element of ruby is chromium. The easiest way to prove its presence in corundum is by observing the absorption spectrum with a pocket spectroscope. Chromium causes a prominent set of absorption lines and a fluorescence doublet in the red part of the spectrum. These characteristics are not visible in the dyed corundum since they lack chromium and therefore are not ruby.
Vietnamese Ruby Salted With Synthetic Ruby
(via ICA Early Warning Flash, no.22, March 27, 1992) Grahame Brown writes:
Background
Following the discovery of alluvial ruby in Vietnam in the late 80s, small parcels of distinctively colored purplish pink to purplish red rough, as well as some cut stones, became available for purchase in Australia in early 1990. Initially the major sellers of this ruby appeared to be Vietnamese residents of Australia. Subsequently, Australian gem merchants purchased parcels of Vietnamese ruby, in Bangkok, for resale in Australia.
Over the last year I have been requested to examine several parcels of Vietnamese ruby rough, as well as some small parcels of faceted Vietnamese ruby, to establish the natural origin of this ruby. This alert has been issued in response to my findings.
Observed features
The rough examined appeared to be water worn, and sometimes displayed visually convincing evidence of external crystal forms, and parting planes. The few unabraded fracture surfaces and parting planes on the surface of this rough allowed very limited visual access to its interior.
Suspicious were immediately raised when some of the rubies, faceted from allegedly Vietnamese ruby rough, displayed:
- diffused curved color banding
- curving empty surface reaching fractures
- profiled gas bubbles and closely associated whitish granular masses
Of these inclusions, the curved color banding was most difficult to detect. Visibility of this curved color banding was enhanced when the immersed ruby was rotated in diffused transmitted light generated from a laterally directed fibre optic wand.
As diffused curved color banding and curving surface reaching fractures characterize heat treated Verneuil synthetic ruby, and profiled bubbles and whitish granular partly melted alumina powder are not uncommonly found in the sintered area of attachment between the Verneuil boule and the ceramic pedestal of the chalumeau……a hypothesis that some parcels of Vietnamese ruby rough were being salted with rough shaped, tumbled, heat treated Verneuil synthetic ruby seems possible.
As some of these inclusions were also observed in small parcels of faceted Vietnamese ruby, buyers of this new exciting should exercise caution.
Background
Following the discovery of alluvial ruby in Vietnam in the late 80s, small parcels of distinctively colored purplish pink to purplish red rough, as well as some cut stones, became available for purchase in Australia in early 1990. Initially the major sellers of this ruby appeared to be Vietnamese residents of Australia. Subsequently, Australian gem merchants purchased parcels of Vietnamese ruby, in Bangkok, for resale in Australia.
Over the last year I have been requested to examine several parcels of Vietnamese ruby rough, as well as some small parcels of faceted Vietnamese ruby, to establish the natural origin of this ruby. This alert has been issued in response to my findings.
Observed features
The rough examined appeared to be water worn, and sometimes displayed visually convincing evidence of external crystal forms, and parting planes. The few unabraded fracture surfaces and parting planes on the surface of this rough allowed very limited visual access to its interior.
Suspicious were immediately raised when some of the rubies, faceted from allegedly Vietnamese ruby rough, displayed:
- diffused curved color banding
- curving empty surface reaching fractures
- profiled gas bubbles and closely associated whitish granular masses
Of these inclusions, the curved color banding was most difficult to detect. Visibility of this curved color banding was enhanced when the immersed ruby was rotated in diffused transmitted light generated from a laterally directed fibre optic wand.
As diffused curved color banding and curving surface reaching fractures characterize heat treated Verneuil synthetic ruby, and profiled bubbles and whitish granular partly melted alumina powder are not uncommonly found in the sintered area of attachment between the Verneuil boule and the ceramic pedestal of the chalumeau……a hypothesis that some parcels of Vietnamese ruby rough were being salted with rough shaped, tumbled, heat treated Verneuil synthetic ruby seems possible.
As some of these inclusions were also observed in small parcels of faceted Vietnamese ruby, buyers of this new exciting should exercise caution.
Blue Diffusion Treated Synthetic Sapphires
(via ICA Early Warning Flash, No.55, June 2, 1992) GIA GTL writes:
Background
Recently the GIA Gem Trade Laboratory, Inc facilities in both Santa Monica, California, and New York, received for identification parcels of faceted stones that were determined to have been diffusion-treated to produce a blue coloration. In one instance, gemological investigation revealed that all three treated stones were synthetic sapphires. In a second instance, a parcel of about 40 stones was determined to consist of approximately 2/3 natural corundums and 1/3 synthetic corundums.
Visible observations/magnification
Examination using immersion with diffused transmitted illumination revealed features characteristic of stone color enhanced through diffusion treatment; for a summary of diagnostic properties, see ‘The Identification of Blue Diffusion Treated Sapphires’ (Kane et al) in the summer 1990 issue of Gems & Gemology.
Using magnification and darkfield illumination it was possible to detect the presence of various inclusions in a number of the stones that identified these hosts as being of natural origin. In other specimens, the presence of gas bubbles proved the hosts to be synthetic. Some stones, however, exhibited no diagnostic features through microscopic examination.
Plato test
The Plato test was also used in the determination of natural vs synthetic origin. A positive Plato test, further substantiating synthetic origin, was obtained with most of the stones identified as synthetic by virtue of diagnostic inclusions, as well as with those specimens without any such internal features. It should be noted, however, that characteristic positive Plato test appearance was generally more subtle than what we are accustomed to seeing.
Ultraviolet luminescence
Examination under both long and short wave ultraviolet radiation revealed some additional potentially useful information. In many cases, the diffusion treated stones exhibited some small areas where there was no blue diffused color, most likely due to this having been removed in repolishing after diffusion treatment. Under long wave UV radiation, these areas on a number of the blue diffusion treated natural sapphires fluoresced reddish orange, a reaction often associated with colorless to light blue corundum from Sri Lanka. When exposed to short wave UV, these same areas fluoresced a chalky whitish blue, a reaction associated with some sapphires that have been exposed to high temperature treatments.
The synthetic sapphires, however, were are all completely inert to long wave UV radiation, including areas where the blue diffusion treated coloration was absent; these areas fluoresced a chalky whitish blue to short wave UV. Such luminescent reactions may be exhibited by colorless synthetic sapphires. While the short wave reactions of both natural and synthetic sapphires were similar in these cases, the effect was slightly stronger with the synthetic samples. It should be noted, however, that the strength of fluorescent reactions in natural, synthetic, and treated sapphires can vary considerably.
Discussion
Immersion used in conjunction with diffused, transmitted illumination is generally quite effective in detecting the presence of diffusion treated color in corundum. Detecting this enhancement, however, does not prove or even indicate whether the treated gem material is of natural or synthetic origin. In the above examples, a combination of magnification and Plato test were used to make this determination.
Ultraviolet luminescence provided some additional, potentially useful information. In this regard, it should be noted that the presence of the reddish orange long wave reaction may be considered a good indication that the starting material is natural; although the absence of such a reaction indicates neither natural nor synthetic origin.
Background
Recently the GIA Gem Trade Laboratory, Inc facilities in both Santa Monica, California, and New York, received for identification parcels of faceted stones that were determined to have been diffusion-treated to produce a blue coloration. In one instance, gemological investigation revealed that all three treated stones were synthetic sapphires. In a second instance, a parcel of about 40 stones was determined to consist of approximately 2/3 natural corundums and 1/3 synthetic corundums.
Visible observations/magnification
Examination using immersion with diffused transmitted illumination revealed features characteristic of stone color enhanced through diffusion treatment; for a summary of diagnostic properties, see ‘The Identification of Blue Diffusion Treated Sapphires’ (Kane et al) in the summer 1990 issue of Gems & Gemology.
Using magnification and darkfield illumination it was possible to detect the presence of various inclusions in a number of the stones that identified these hosts as being of natural origin. In other specimens, the presence of gas bubbles proved the hosts to be synthetic. Some stones, however, exhibited no diagnostic features through microscopic examination.
Plato test
The Plato test was also used in the determination of natural vs synthetic origin. A positive Plato test, further substantiating synthetic origin, was obtained with most of the stones identified as synthetic by virtue of diagnostic inclusions, as well as with those specimens without any such internal features. It should be noted, however, that characteristic positive Plato test appearance was generally more subtle than what we are accustomed to seeing.
Ultraviolet luminescence
Examination under both long and short wave ultraviolet radiation revealed some additional potentially useful information. In many cases, the diffusion treated stones exhibited some small areas where there was no blue diffused color, most likely due to this having been removed in repolishing after diffusion treatment. Under long wave UV radiation, these areas on a number of the blue diffusion treated natural sapphires fluoresced reddish orange, a reaction often associated with colorless to light blue corundum from Sri Lanka. When exposed to short wave UV, these same areas fluoresced a chalky whitish blue, a reaction associated with some sapphires that have been exposed to high temperature treatments.
The synthetic sapphires, however, were are all completely inert to long wave UV radiation, including areas where the blue diffusion treated coloration was absent; these areas fluoresced a chalky whitish blue to short wave UV. Such luminescent reactions may be exhibited by colorless synthetic sapphires. While the short wave reactions of both natural and synthetic sapphires were similar in these cases, the effect was slightly stronger with the synthetic samples. It should be noted, however, that the strength of fluorescent reactions in natural, synthetic, and treated sapphires can vary considerably.
Discussion
Immersion used in conjunction with diffused, transmitted illumination is generally quite effective in detecting the presence of diffusion treated color in corundum. Detecting this enhancement, however, does not prove or even indicate whether the treated gem material is of natural or synthetic origin. In the above examples, a combination of magnification and Plato test were used to make this determination.
Ultraviolet luminescence provided some additional, potentially useful information. In this regard, it should be noted that the presence of the reddish orange long wave reaction may be considered a good indication that the starting material is natural; although the absence of such a reaction indicates neither natural nor synthetic origin.
Tuesday, April 24, 2007
Synthetic Green Quartz
(via ICA Early Warning Flash, No. 63, November 17, 1992) GIA GTL writes:
Background
At the Tucson Gem and Mineral shows in February of 1991, we noted dealers offering large quantities of synthetic quartz, reportedly of Russian origin. Among these was a transparent dark green type that visually resembles tourmaline. This green synthetic quartz was also being offered at the Tucson shows this past February; it was our impression that even more faceted material was being offered this year.
Recently, the GIA Gem Trade Laboratory, Inc in Santa Monica received for identification from two separate clients faceted specimens of what we identified as dark green synthetic quartz. In both cases, the material has been represented to our clients as a new type of natural green quartz from Brazil.
Gemological properties
Gemological testing revealed refractive indices, birefringence, and specific gravity consistent with quartz, both natural and synthetic. The specimens were inert to both long and short wave ultraviolet radiation.
Examination under immersion between crossed polaroids shows that the material was untwined, with a bulls eye optical interference figure. Under magnification we noted parallel green color banding similar to that seen in a reference sample of synthetic green quartz of Russian origin. Also noted was some angular brown color zoning that ran perpendicular to the green banding, a feature we have noted in other colors of hydrothermal synthetic quartz. One specimen also contained numerous tiny white pinpoint inclusions of undetermined origin.
Chemistry
Energy Dispersive X-ray fluorescence detected the presence of silicon, potassium, and iron. This differed only slightly from the chemistry of the synthetic green quartz reference specimen. It is believed that the iron detected is responsible for the green coloration.
Discussion
In the above cases, the client’s specimens were all identified as synthetic green quartz. It is important to note that, while green quartz does occur in nature (and is sometimes referred to as praseolite or prasiolita), such material is typically light in tone. To our knowledge, natural green quartz with this depth of color has not been reported.
Background
At the Tucson Gem and Mineral shows in February of 1991, we noted dealers offering large quantities of synthetic quartz, reportedly of Russian origin. Among these was a transparent dark green type that visually resembles tourmaline. This green synthetic quartz was also being offered at the Tucson shows this past February; it was our impression that even more faceted material was being offered this year.
Recently, the GIA Gem Trade Laboratory, Inc in Santa Monica received for identification from two separate clients faceted specimens of what we identified as dark green synthetic quartz. In both cases, the material has been represented to our clients as a new type of natural green quartz from Brazil.
Gemological properties
Gemological testing revealed refractive indices, birefringence, and specific gravity consistent with quartz, both natural and synthetic. The specimens were inert to both long and short wave ultraviolet radiation.
Examination under immersion between crossed polaroids shows that the material was untwined, with a bulls eye optical interference figure. Under magnification we noted parallel green color banding similar to that seen in a reference sample of synthetic green quartz of Russian origin. Also noted was some angular brown color zoning that ran perpendicular to the green banding, a feature we have noted in other colors of hydrothermal synthetic quartz. One specimen also contained numerous tiny white pinpoint inclusions of undetermined origin.
Chemistry
Energy Dispersive X-ray fluorescence detected the presence of silicon, potassium, and iron. This differed only slightly from the chemistry of the synthetic green quartz reference specimen. It is believed that the iron detected is responsible for the green coloration.
Discussion
In the above cases, the client’s specimens were all identified as synthetic green quartz. It is important to note that, while green quartz does occur in nature (and is sometimes referred to as praseolite or prasiolita), such material is typically light in tone. To our knowledge, natural green quartz with this depth of color has not been reported.
Synthetic Green Quartz
(via ICA Early Warning Flash, No. 63, November 17, 1992) GIA GTL writes:
Background
At the Tucson Gem and Mineral shows in February of 1991, we noted dealers offering large quantities of synthetic quartz, reportedly of Russian origin. Among these was a transparent dark green type that visually resembles tourmaline. This green synthetic quartz was also being offered at the Tucson shows this past February; it was our impression that even more faceted material was being offered this year.
Recently, the GIA Gem Trade Laboratory, Inc in Santa Monica received for identification from two separate clients faceted specimens of what we identified as dark green synthetic quartz. In both cases, the material has been represented to our clients as a new type of natural green quartz from Brazil.
Gemological properties
Gemological testing revealed refractive indices, birefringence, and specific gravity consistent with quartz, both natural and synthetic. The specimens were inert to both long and short wave ultraviolet radiation.
Examination under immersion between crossed polaroids shows that the material was untwined, with a bulls eye optical interference figure. Under magnification we noted parallel green color banding similar to that seen in a reference sample of synthetic green quartz of Russian origin. Also noted was some angular brown color zoning that ran perpendicular to the green banding, a feature we have noted in other colors of hydrothermal synthetic quartz. One specimen also contained numerous tiny white pinpoint inclusions of undetermined origin.
Chemistry
Energy Dispersive X-ray fluorescence detected the presence of silicon, potassium, and iron. This differed only slightly from the chemistry of the synthetic green quartz reference specimen. It is believed that the iron detected is responsible for the green coloration.
Discussion
In the above cases, the client’s specimens were all identified as synthetic green quartz. It is important to note that, while green quartz does occur in nature (and is sometimes referred to as praseolite or prasiolita), such material is typically light in tone. To our knowledge, natural green quartz with this depth of color has not been reported.
Background
At the Tucson Gem and Mineral shows in February of 1991, we noted dealers offering large quantities of synthetic quartz, reportedly of Russian origin. Among these was a transparent dark green type that visually resembles tourmaline. This green synthetic quartz was also being offered at the Tucson shows this past February; it was our impression that even more faceted material was being offered this year.
Recently, the GIA Gem Trade Laboratory, Inc in Santa Monica received for identification from two separate clients faceted specimens of what we identified as dark green synthetic quartz. In both cases, the material has been represented to our clients as a new type of natural green quartz from Brazil.
Gemological properties
Gemological testing revealed refractive indices, birefringence, and specific gravity consistent with quartz, both natural and synthetic. The specimens were inert to both long and short wave ultraviolet radiation.
Examination under immersion between crossed polaroids shows that the material was untwined, with a bulls eye optical interference figure. Under magnification we noted parallel green color banding similar to that seen in a reference sample of synthetic green quartz of Russian origin. Also noted was some angular brown color zoning that ran perpendicular to the green banding, a feature we have noted in other colors of hydrothermal synthetic quartz. One specimen also contained numerous tiny white pinpoint inclusions of undetermined origin.
Chemistry
Energy Dispersive X-ray fluorescence detected the presence of silicon, potassium, and iron. This differed only slightly from the chemistry of the synthetic green quartz reference specimen. It is believed that the iron detected is responsible for the green coloration.
Discussion
In the above cases, the client’s specimens were all identified as synthetic green quartz. It is important to note that, while green quartz does occur in nature (and is sometimes referred to as praseolite or prasiolita), such material is typically light in tone. To our knowledge, natural green quartz with this depth of color has not been reported.
Maxixe Type Beryls
(via ICA Early Warning Flash, No.72, July 29, 1993) Grahame Brown writes:
Preamble
Maxixe-type beryls are potentially color fading, strongly hued blue, green, blue green, yellow green, and yellow beryls that have been created by irradiation and selective heat treatment of previously pale to light colored beryl that has a very specific precursor color center.
Although the identifying features of color fading deep blue and deep green Maxixe-type beryls have been known since the early 1970s, little information has been published about the identifying features of color fading strongly hued greenish yellow to yellow green Maxixe-type beryls, or more importantly, somewhat color stable yellow Maxixe-type beryls.
While dark blue and less common dark green Maxixe-type beryls first appeared on world gem markets about 20 years ago, the recent appearance of well faceted, large size (<20 ct), eye clean, strongly hued greenish yellow, yellow green, and yellow Maxixe-type beryls may indicate renewed interest in the manufacture of these color enhanced beryls.
Identification
Irrespective of color, or whether or not the rough has or has not been oriented to display best color through the table of the faceted beryl, Maxixe-type beryls can be identified by:
An essential first step:
Using a conoscope, or equivalent gemological instrument such as a Snow Figure-O-Scope to accurately locate the optic axis (direction of single refraction or direction of the ordinary ray) in the suspect beryl.
As essential second step:
Examine the beryl, in the direction of its ordinary ray, with a hand-held dichroscope. If the beryl is a Maxixe-type, two adjacent dark color (of equal strength) will be observed. In contrast, if the beryl is a naturally colored aquamarine or heliodor, two light color (of equal strength) will be observed.
A confirmatory third step:
Examine the beryl, in the direction of its ordinary ray, with a prism or diffraction grating spectroscope. If the beryl is not examined, precisely along the direction of its ordinary ray, identifying Maxixe-type absorptions, that consist of a distinctive pattern of narrow absorptions of varying strength between 700nm (red) and 550nm (green), may not be observed.
Fade testing by exposing the suspect beryl to intense sunlight for more than a week, or by heating it for 30 minutes at 200-450 F, or by exposing it to a 100 W incandescent light bulb for 150 hours at a distance of 15cm, is an undesirable, destructive form of gem testing.
Consequently this ultimate test of fading potential is unlikely to be applied, except in the research laboratory.
However, in spite of this obvious limitation, fade testing does not provide the ultimate test for color stability. Under any of the fade testing conditions specified above:
Deep blue Maxixe-type beryls do not fade rapidly, and dramatically.
Greenish yellow to yellow green Maxixe-type beryls essentially loose their greenish component and fade to a yellowish hue.
Yellow Maxixe-type beryls loose any green component in their color, and may also fade.
Preamble
Maxixe-type beryls are potentially color fading, strongly hued blue, green, blue green, yellow green, and yellow beryls that have been created by irradiation and selective heat treatment of previously pale to light colored beryl that has a very specific precursor color center.
Although the identifying features of color fading deep blue and deep green Maxixe-type beryls have been known since the early 1970s, little information has been published about the identifying features of color fading strongly hued greenish yellow to yellow green Maxixe-type beryls, or more importantly, somewhat color stable yellow Maxixe-type beryls.
While dark blue and less common dark green Maxixe-type beryls first appeared on world gem markets about 20 years ago, the recent appearance of well faceted, large size (<20 ct), eye clean, strongly hued greenish yellow, yellow green, and yellow Maxixe-type beryls may indicate renewed interest in the manufacture of these color enhanced beryls.
Identification
Irrespective of color, or whether or not the rough has or has not been oriented to display best color through the table of the faceted beryl, Maxixe-type beryls can be identified by:
An essential first step:
Using a conoscope, or equivalent gemological instrument such as a Snow Figure-O-Scope to accurately locate the optic axis (direction of single refraction or direction of the ordinary ray) in the suspect beryl.
As essential second step:
Examine the beryl, in the direction of its ordinary ray, with a hand-held dichroscope. If the beryl is a Maxixe-type, two adjacent dark color (of equal strength) will be observed. In contrast, if the beryl is a naturally colored aquamarine or heliodor, two light color (of equal strength) will be observed.
A confirmatory third step:
Examine the beryl, in the direction of its ordinary ray, with a prism or diffraction grating spectroscope. If the beryl is not examined, precisely along the direction of its ordinary ray, identifying Maxixe-type absorptions, that consist of a distinctive pattern of narrow absorptions of varying strength between 700nm (red) and 550nm (green), may not be observed.
Fade testing by exposing the suspect beryl to intense sunlight for more than a week, or by heating it for 30 minutes at 200-450 F, or by exposing it to a 100 W incandescent light bulb for 150 hours at a distance of 15cm, is an undesirable, destructive form of gem testing.
Consequently this ultimate test of fading potential is unlikely to be applied, except in the research laboratory.
However, in spite of this obvious limitation, fade testing does not provide the ultimate test for color stability. Under any of the fade testing conditions specified above:
Deep blue Maxixe-type beryls do not fade rapidly, and dramatically.
Greenish yellow to yellow green Maxixe-type beryls essentially loose their greenish component and fade to a yellowish hue.
Yellow Maxixe-type beryls loose any green component in their color, and may also fade.
Fracture-filled Fancy Pink Diamond
(via ICA Early Warning Flash, No.65, December 21, 1992) GAGTL writes:
A pink cut-cornered square modified brilliant diamond was submitted to the Gem Testing Laboratory for the determination of the origin of its color—whether it was of natural or treated color and for the determination of the color grade.
The diamond weighed 3.35 carats and measured approx. 8.32x8.08x6.53mm. Upon examination with a 10x lens, one was struck by the many feathers visible within the stone. Viewing the diamond from various angles and by transmitted light, one could detect many surface reaching fractures displaying iridescent colors implying these were filled with air. But also noticeable were the tell-tale blue and orange flashes in some fractures indicating that these had been filled with an artificial material.
Spectroscopic investigation of the stone proved it to be a diamond of natural color and of type IaAB. The nature of the internal colored grain lines and the frosted appearance of some of the fractures indicated that the diamond may have been mined in Argyle, Australia.
If graded, the color grade would be fancy pink and the clarity grade would be pique III. However, The Gem Testing Laboratory does not issue grading reports on fracture filled diamonds. The poor clarity grade apparent subsequent to fracture treatment and the presence of untreated air-filled fractures indicate that the clarity enhancement process was not successful.
Although the Laboratory has tested fracture-filled diamonds before, this is the first instance we have seen of a fancy colored diamond being so treated.
A pink cut-cornered square modified brilliant diamond was submitted to the Gem Testing Laboratory for the determination of the origin of its color—whether it was of natural or treated color and for the determination of the color grade.
The diamond weighed 3.35 carats and measured approx. 8.32x8.08x6.53mm. Upon examination with a 10x lens, one was struck by the many feathers visible within the stone. Viewing the diamond from various angles and by transmitted light, one could detect many surface reaching fractures displaying iridescent colors implying these were filled with air. But also noticeable were the tell-tale blue and orange flashes in some fractures indicating that these had been filled with an artificial material.
Spectroscopic investigation of the stone proved it to be a diamond of natural color and of type IaAB. The nature of the internal colored grain lines and the frosted appearance of some of the fractures indicated that the diamond may have been mined in Argyle, Australia.
If graded, the color grade would be fancy pink and the clarity grade would be pique III. However, The Gem Testing Laboratory does not issue grading reports on fracture filled diamonds. The poor clarity grade apparent subsequent to fracture treatment and the presence of untreated air-filled fractures indicate that the clarity enhancement process was not successful.
Although the Laboratory has tested fracture-filled diamonds before, this is the first instance we have seen of a fancy colored diamond being so treated.
Hydrothermal Synthetic Rubies
(via ICA Early Warning Flash, No.66, January 28, 1993) GGL writes:
Background
During the Fall season of 1991, we first became aware of a production of hydrothermal synthetic rubies being made in Russia. At that time, we were informed that the production was only consisting of very small stones and therefore this seemed to be more of a scientific than commercial interest. During the next year and a half, we did not receive any additional information concerning further developments of this product. While on a recent trip to Bangkok though three samples were acquired which were reportedly from a recent production of Russian hydrothermal synthetic rubies. Seeing as how this represents a new and therefore unfamiliar synthetic ruby on the market, we felt it would be beneficial to inform the colored stone industry of their presence through the ICA Early Warning Alert system.
Gemological properties
The three sample stones tested, weighed 1.69, 0.69 and 0.62 ct. possessing colors ranging from Burma to Thai types with high saturations and medium to dark tones. Standard gemological testing revealed properties of refractive index (1.76-1.77), birefringence (0.008), specific gravity (3.99-4.00), UV fluorescence (LW: weak-med, red; SW: inert-weak red) and spectrum, consistent with other natural and synthetic rubies.
Microscopic examination revealed the presence of very strong graining features throughout the stone. These graining features are visually reminiscent of the type of graining observed in the Russian production of hydrothermal synthetic emeralds. In most directions, this graining is generally in a striated pattern, although in one direction the graining takes on a strongly roiled appearance resembling an aggregation of graining features. The presence of this graining is so strong, as to have an effect of slightly reducing the transparency of the stone enough to give it a sleepy appearance. This also caused a slightly diffused image of the pavilion back facet edges when viewed through the table. Certain fluctuations of color zoning could also be observed interwoven with the graining patterns. Distinctive as well were the presence of numerous, small, golden colored, highly reflective metallic inclusions. These inclusions were present in small collective groups as well as sparsely located individually. Additionally observed were healed fracture systems creating fingerprint inclusions which occasionally contained a secondary gas phase and other fracture systems.
Discussion
While these rubies represent a completely new kind of synthetic which could be encountered in the market today, their identification should not prove to be difficult. Just as with other synthetic rubies, mass sampling by means of UV fluorescence will not separate these synthetics from their natural counterparts. Microscopic examination identifying the very strong graining features which are unlike any of the swirled or planar growth characteristics observed in natural rubies from various localities and the presence of golden colored metallic inclusions, provide clear and easy proof of the synthetic origin for these hydrothermally grown rubies.
Background
During the Fall season of 1991, we first became aware of a production of hydrothermal synthetic rubies being made in Russia. At that time, we were informed that the production was only consisting of very small stones and therefore this seemed to be more of a scientific than commercial interest. During the next year and a half, we did not receive any additional information concerning further developments of this product. While on a recent trip to Bangkok though three samples were acquired which were reportedly from a recent production of Russian hydrothermal synthetic rubies. Seeing as how this represents a new and therefore unfamiliar synthetic ruby on the market, we felt it would be beneficial to inform the colored stone industry of their presence through the ICA Early Warning Alert system.
Gemological properties
The three sample stones tested, weighed 1.69, 0.69 and 0.62 ct. possessing colors ranging from Burma to Thai types with high saturations and medium to dark tones. Standard gemological testing revealed properties of refractive index (1.76-1.77), birefringence (0.008), specific gravity (3.99-4.00), UV fluorescence (LW: weak-med, red; SW: inert-weak red) and spectrum, consistent with other natural and synthetic rubies.
Microscopic examination revealed the presence of very strong graining features throughout the stone. These graining features are visually reminiscent of the type of graining observed in the Russian production of hydrothermal synthetic emeralds. In most directions, this graining is generally in a striated pattern, although in one direction the graining takes on a strongly roiled appearance resembling an aggregation of graining features. The presence of this graining is so strong, as to have an effect of slightly reducing the transparency of the stone enough to give it a sleepy appearance. This also caused a slightly diffused image of the pavilion back facet edges when viewed through the table. Certain fluctuations of color zoning could also be observed interwoven with the graining patterns. Distinctive as well were the presence of numerous, small, golden colored, highly reflective metallic inclusions. These inclusions were present in small collective groups as well as sparsely located individually. Additionally observed were healed fracture systems creating fingerprint inclusions which occasionally contained a secondary gas phase and other fracture systems.
Discussion
While these rubies represent a completely new kind of synthetic which could be encountered in the market today, their identification should not prove to be difficult. Just as with other synthetic rubies, mass sampling by means of UV fluorescence will not separate these synthetics from their natural counterparts. Microscopic examination identifying the very strong graining features which are unlike any of the swirled or planar growth characteristics observed in natural rubies from various localities and the presence of golden colored metallic inclusions, provide clear and easy proof of the synthetic origin for these hydrothermally grown rubies.
Diamond Fracture Filling Extensive Treatment, Subtle Features
(via ICA Early Warning Flash, No.68, April 5, 1993) GIA GTL writes:
Background
The diamond described herein is a 0.88 carat heat-shaped brilliant that was initially submitted to the GIA Gem Trade Laboratory for grading. During preliminary examination, however, a staff gemologist noted at first appeared to be an extremely low relief fingerprint inclusion containing minute voids. As this would be very atypical for diamond, the stone was brought to the identification and research lab for investigation.
Microscopic features
Examination under magnification using standard darkfield illumination revealed several very transparent, colorless, filled fractures. These all contained minute voids as mentioned above, as well very subtle orange and, to a lesser extent, blue flash effects. Difficulty in detecting these effects was compounded by the very shallow angles of the fractures to the surface of the diamond.
The treatment became more apparent when a pinpoint fiber optic illuminator was used. This lighting technique revealed the extent of the filled breaks, including one very large fracture beneath and nearly parallel to the table. The intense illumination made the flash effects significantly more noticeable, as well as revealing hairline fractures in the filling material. The outlines of the filled areas were also found to be easier to detect when examined in transmitted lighting with a single polarizing filter placed between the microscope’s objectives and the diamond.
Additional testing
Qualitative chemical analysis using energy dispersive X-ray fluorescence detected lead, an element previously detected in diamond fillings, X-radiography further confirmed the presence of the filling in the form of white, X-ray opaque areas on the radiograph.
Discussion
Although the diamond under investigation contained extensive filled fractures, the diagnostic microscopic features of the treatment were quite subtle. These might easily be overlooked if only darkfield illumination were used. It is therefore recommended that additional lighting techniques be used when examining diamonds for possible filled breaks, including pinpoint fiberoptic illumination and polarized light.
Background
The diamond described herein is a 0.88 carat heat-shaped brilliant that was initially submitted to the GIA Gem Trade Laboratory for grading. During preliminary examination, however, a staff gemologist noted at first appeared to be an extremely low relief fingerprint inclusion containing minute voids. As this would be very atypical for diamond, the stone was brought to the identification and research lab for investigation.
Microscopic features
Examination under magnification using standard darkfield illumination revealed several very transparent, colorless, filled fractures. These all contained minute voids as mentioned above, as well very subtle orange and, to a lesser extent, blue flash effects. Difficulty in detecting these effects was compounded by the very shallow angles of the fractures to the surface of the diamond.
The treatment became more apparent when a pinpoint fiber optic illuminator was used. This lighting technique revealed the extent of the filled breaks, including one very large fracture beneath and nearly parallel to the table. The intense illumination made the flash effects significantly more noticeable, as well as revealing hairline fractures in the filling material. The outlines of the filled areas were also found to be easier to detect when examined in transmitted lighting with a single polarizing filter placed between the microscope’s objectives and the diamond.
Additional testing
Qualitative chemical analysis using energy dispersive X-ray fluorescence detected lead, an element previously detected in diamond fillings, X-radiography further confirmed the presence of the filling in the form of white, X-ray opaque areas on the radiograph.
Discussion
Although the diamond under investigation contained extensive filled fractures, the diagnostic microscopic features of the treatment were quite subtle. These might easily be overlooked if only darkfield illumination were used. It is therefore recommended that additional lighting techniques be used when examining diamonds for possible filled breaks, including pinpoint fiberoptic illumination and polarized light.
Diffusion Treated Corundum In Pink To Red To Purple Color Range
(via ICA Early Warning Flash, No.69, May 14, 1993) GIA GTL writes:
Background
The diffusion treated stones described herein were provided for examination by United Radiant Applications, a Southern California-based firm that has been involved in the commercial production of blue diffusion treated sapphires. The faceted specimens, which included 27 stones in the red to pink to purple color range, were made available so that their gemological properties and identification criteria could be documented prior to any commercial release.
Visual appearance
Face-up some of the stones appear uniform in color, while other exhibit uneven color distribution, the latter apparently due to an absence of color on some pavilion facets.
Magnification
A number of features previously documented with blue diffusion treated sapphires were noted in these stones. These include uneven coloration from one facet to another, color concentrations in surface-reaching cavities and fractures, and color reinforcement of facet junctions, although the latter was often significantly more subtle than what we have encountered with blue diffusion-treated stones. Also noted was a type of surface and near surface damage, including minute spherical voids that we had not previously documented in blue diffusion treated sapphires.
Refractive indices
Values were generally higher than those normal for corundum, including some reading over the limits of the conventional refractometer (1.80 +).
Pleochroism
Some stones exhibited atypical dichroism, including a brownish yellow dichroic color.
Short wave UV luminescence
The majority of the stones showed a patchy bluish white luminescence to this wavelength at the surface that was sometimes confined to specific facets or groups of facets.
Absorption spectra
These were generally consistent with those of both natural and synthetic corundums of comparable color, although some absorption features were less pronounced.
Discussion
The diffusion treated corundums described herein are not difficult to identify. Key features include unusually high refractive index readings, atypical dichroism and UV luminescence, patchy surface coloration, color concentrations along facet junctions, and spherical voids just below the surface.
Background
The diffusion treated stones described herein were provided for examination by United Radiant Applications, a Southern California-based firm that has been involved in the commercial production of blue diffusion treated sapphires. The faceted specimens, which included 27 stones in the red to pink to purple color range, were made available so that their gemological properties and identification criteria could be documented prior to any commercial release.
Visual appearance
Face-up some of the stones appear uniform in color, while other exhibit uneven color distribution, the latter apparently due to an absence of color on some pavilion facets.
Magnification
A number of features previously documented with blue diffusion treated sapphires were noted in these stones. These include uneven coloration from one facet to another, color concentrations in surface-reaching cavities and fractures, and color reinforcement of facet junctions, although the latter was often significantly more subtle than what we have encountered with blue diffusion-treated stones. Also noted was a type of surface and near surface damage, including minute spherical voids that we had not previously documented in blue diffusion treated sapphires.
Refractive indices
Values were generally higher than those normal for corundum, including some reading over the limits of the conventional refractometer (1.80 +).
Pleochroism
Some stones exhibited atypical dichroism, including a brownish yellow dichroic color.
Short wave UV luminescence
The majority of the stones showed a patchy bluish white luminescence to this wavelength at the surface that was sometimes confined to specific facets or groups of facets.
Absorption spectra
These were generally consistent with those of both natural and synthetic corundums of comparable color, although some absorption features were less pronounced.
Discussion
The diffusion treated corundums described herein are not difficult to identify. Key features include unusually high refractive index readings, atypical dichroism and UV luminescence, patchy surface coloration, color concentrations along facet junctions, and spherical voids just below the surface.
Mixed Diamonds & Octahedral Cubic Zirconia Baguettes
(via ICA Early Warning Flash, No.73, August 13, 1993) GII writes:
Recently we have encountered in a packet of rough diamond one octahedral shaped cubic zirconia. The person who had done this also must be having some idea of crystallography for he has taken the trouble to etch out trigons on the octahedral faces. Fortunately, the trigons are parallel to the sides of the octahedral faces, whereas in diamonds they are not; this gave us the first doubt and other tests confirmed our suspicion.
Another interesting case of cubic zirconia fraud has also been detected at our laboratory. In a packet of diamond baguettes as well as round brilliant same sized cubic zirconia baguettes and round brilliants were detected. The suspicion was first triggered off when similar dimension baguettes were weighing 0.029 carats and some 0.05. The difference was obvious when the weight of some more number of pieces was compared and other tests were performed.
Recently we have encountered in a packet of rough diamond one octahedral shaped cubic zirconia. The person who had done this also must be having some idea of crystallography for he has taken the trouble to etch out trigons on the octahedral faces. Fortunately, the trigons are parallel to the sides of the octahedral faces, whereas in diamonds they are not; this gave us the first doubt and other tests confirmed our suspicion.
Another interesting case of cubic zirconia fraud has also been detected at our laboratory. In a packet of diamond baguettes as well as round brilliant same sized cubic zirconia baguettes and round brilliants were detected. The suspicion was first triggered off when similar dimension baguettes were weighing 0.029 carats and some 0.05. The difference was obvious when the weight of some more number of pieces was compared and other tests were performed.
Synthetic Diamonds: Rough And Treated, Faceted
(via ICA Early Warning Flash, No.74, August 13, 1993) GIA GTL writes:
Background
Recently a 0.74 carat yellow rough crystal was submitted to the GIA Gem Trade Laboratory in New York for routine identification. Shortly thereafter, a 0.55 carat dark brownish orangy red round brilliant was submitted to GIA GTL for an origin of color determination. Examination of both specimens revealed that they were synthetic diamonds. It was further determined that the rough specimen had been annealed and that the faceted one had been irradiated and subsequently annealed.
Appearance
The habit of the rough crystal was predominantly cubic, with some octahedral and dodecahedral faces. Smooth cube, and to a lesser extent, dodecahedral, faces are seen only on synthetic diamonds.
Magnification/magnetism
Both the rough and faceted pieces contained fairly large inclusions with a metallic luster. When suspended at the end of a thread, both were attached to a magnet, actually attaching to it. This reaction has been noted to date only with synthetic diamonds containing large, magnetic inclusions derived from the metallic flux in which they are produced.
The two showed similar patterns of ultraviolet luminescence and color zoning, forming essentially a square; the faceted piece also revealed this in the form of graining. This growth pattern was centered roughly in the middle of the base of the crystal and on the table of the round brilliant. Octagonal to square patterns are commonly seen in synthetic diamonds, but not in natural diamonds.
Ultraviolet luminescence
The ultraviolet luminescence of both pieces was stronger in short wave than long wave radiation. They both emitted a moderate to strong green fluorescence along the pattern described above in short wave UV radiation, with a weaker green reaction in long wave. The round brilliant also emitted a moderate orange fluorescence in short wave. Gem quality yellow synthetic diamonds previously examined by GIA Research and GIA GTL personnel have shown luminescence in short wave exclusively. The reactions noted in the two specimens under discussion would therefore appear to be from a source other than those we have previously documented in the gemological literature.
UV/Visible/IR spectroscopy
Spectroscopy helped to further characterize the specimens. Infrared spectroscopy showed them both to be essentially type Ib, as are most yellow synthetic diamonds. However, they both also showed a IaA character. This has not previously been observed in gem quality synthetic diamonds.
In the visible range, the round brilliant showed a number of sharp lines between 500 and 700bn at liquid nitrogen temperature. These features were noted both in the hand held spectroscope and on the chart of the spectrometer. Some of these lines have never been observed in natural diamond but have been reported in synthetic diamonds.
Finally, the presence of the features typical of treated pink diamonds in the spectrum of the red brilliant (in addition to other lines mentioned above) and a small HIb peak in the infrared prove that it had been irradiated and subsequently annealed. The yellow crystal also shows a line at about 637nm, which suggests that it, too, had been subjected to annealing.
Conclusion
The above characteristics clearly identify both the crystal and round brilliant as synthetic diamonds. However, some of their properties are slightly different from what we have observed before in yellow gem quality synthetic diamonds. Interestingly, virtually all the features noted are consistent with those of a group of Russian yellow synthetic diamonds currently being studied by GIA Research and the GIA GTL.
Background
Recently a 0.74 carat yellow rough crystal was submitted to the GIA Gem Trade Laboratory in New York for routine identification. Shortly thereafter, a 0.55 carat dark brownish orangy red round brilliant was submitted to GIA GTL for an origin of color determination. Examination of both specimens revealed that they were synthetic diamonds. It was further determined that the rough specimen had been annealed and that the faceted one had been irradiated and subsequently annealed.
Appearance
The habit of the rough crystal was predominantly cubic, with some octahedral and dodecahedral faces. Smooth cube, and to a lesser extent, dodecahedral, faces are seen only on synthetic diamonds.
Magnification/magnetism
Both the rough and faceted pieces contained fairly large inclusions with a metallic luster. When suspended at the end of a thread, both were attached to a magnet, actually attaching to it. This reaction has been noted to date only with synthetic diamonds containing large, magnetic inclusions derived from the metallic flux in which they are produced.
The two showed similar patterns of ultraviolet luminescence and color zoning, forming essentially a square; the faceted piece also revealed this in the form of graining. This growth pattern was centered roughly in the middle of the base of the crystal and on the table of the round brilliant. Octagonal to square patterns are commonly seen in synthetic diamonds, but not in natural diamonds.
Ultraviolet luminescence
The ultraviolet luminescence of both pieces was stronger in short wave than long wave radiation. They both emitted a moderate to strong green fluorescence along the pattern described above in short wave UV radiation, with a weaker green reaction in long wave. The round brilliant also emitted a moderate orange fluorescence in short wave. Gem quality yellow synthetic diamonds previously examined by GIA Research and GIA GTL personnel have shown luminescence in short wave exclusively. The reactions noted in the two specimens under discussion would therefore appear to be from a source other than those we have previously documented in the gemological literature.
UV/Visible/IR spectroscopy
Spectroscopy helped to further characterize the specimens. Infrared spectroscopy showed them both to be essentially type Ib, as are most yellow synthetic diamonds. However, they both also showed a IaA character. This has not previously been observed in gem quality synthetic diamonds.
In the visible range, the round brilliant showed a number of sharp lines between 500 and 700bn at liquid nitrogen temperature. These features were noted both in the hand held spectroscope and on the chart of the spectrometer. Some of these lines have never been observed in natural diamond but have been reported in synthetic diamonds.
Finally, the presence of the features typical of treated pink diamonds in the spectrum of the red brilliant (in addition to other lines mentioned above) and a small HIb peak in the infrared prove that it had been irradiated and subsequently annealed. The yellow crystal also shows a line at about 637nm, which suggests that it, too, had been subjected to annealing.
Conclusion
The above characteristics clearly identify both the crystal and round brilliant as synthetic diamonds. However, some of their properties are slightly different from what we have observed before in yellow gem quality synthetic diamonds. Interestingly, virtually all the features noted are consistent with those of a group of Russian yellow synthetic diamonds currently being studied by GIA Research and the GIA GTL.
Saturday, April 21, 2007
Polymer-impregnated Jadeite
(via ICA Early Warning Flash, No.75, November 23, 1993) GIA GTL writes:
Background
Over the last several years polymer-impregnated jadeite has become prevalent in the jade market. This has given rise to some colors of jadeite being routinely tested for the presence of this treatment.
Recently, the GIA GTL in Santa Monica received for identification a 15 carat purple oval cabochon that we identified as jadeite. Subsequent testing determined the stone to be polymer impregnated. To the best of our knowledge, this is the first report of a jadeite of this color that is polymer-impregnated.
Polymer-impregnated ‘lavender’ jadeite
Gemological properties: Gemological testing revealed an index of refraction and visible absorption spectrum consistent with jadeite jade. Specific gravity was measured by the hydrostatic method and determined to be 3.32, which is slightly lower than the norm for jadeite. This is consistent with previous findings of polymer-impregnated jadeite. The stone was inert to longwave ultraviolet radiation. Magnification did not reveal any evidence of treatment. As is often the case with purple jadeite, the origin of the color could be be determined.
Infrared spectroscopy
The spectrum of this stone reveals intense absorptions around 2900cm¯¹ which are not found in natural jadeite. These additional features are due to the presence of an ‘opticon-like’ polymer. This is not surprising, since this type of polymer is the most commonly employed for jadeite impregnation, according to many reports and our own experience.
Discussion
This finding is particularly significant since none of the polymer-impregnated jadeite (or B jade) we have seen so far was purple in color. They have all been green or mottled green and white, some with applied spots of brown. This means that we will now have to expand our routine testing for polymer impregnation to include purple jadeites as well.
New polymers for jadeite impregnation
We have recently encountered two new types of polymer used for the treatment of jadeite, in addition to the three previously described which are wax, an ‘opticon-like’ polymer, and phthalate-like polymer. Since we do not know yet their exact nature, we will refer to them as polymer 4 and polymer 5.
Polymer 4
The infrared spectrum of polymer 4 is very similar—but not identical—to that of wax. In particular, the major absorption is slightly shifted and of different width than that for wax. Jadeites treated with this product do not ‘sweat’ when tested with the thermal reaction tester, as opposed to those impregnated with wax which do. We measured the SG of one stone showing this kind of impregnation at 3.33.
Polymer 5
The infrared spectrum of polymer 5 shows similar absorption features as polymer 4, plus five more in the range of 2950-3150 cm¯¹. The three jadeites impregnated with this material that we studied are inert in ultraviolet radiation. We could measure the SG on only one of them, and the stone floated in the 3.32 SG liquid (methylene iodide). It is interesting to note that two of these stones displayed ‘sweating’ when tested with T.R.T.
Conclusion
These two new polymers have been seen on a few jadeites submitted for identification, and laboratories involved in B-jade detection should be aware of them. They demonstrate the growing variety of polymers that are being used for jade treatment. One reason for this could be the increasing number of companies involved in this treatment.
Background
Over the last several years polymer-impregnated jadeite has become prevalent in the jade market. This has given rise to some colors of jadeite being routinely tested for the presence of this treatment.
Recently, the GIA GTL in Santa Monica received for identification a 15 carat purple oval cabochon that we identified as jadeite. Subsequent testing determined the stone to be polymer impregnated. To the best of our knowledge, this is the first report of a jadeite of this color that is polymer-impregnated.
Polymer-impregnated ‘lavender’ jadeite
Gemological properties: Gemological testing revealed an index of refraction and visible absorption spectrum consistent with jadeite jade. Specific gravity was measured by the hydrostatic method and determined to be 3.32, which is slightly lower than the norm for jadeite. This is consistent with previous findings of polymer-impregnated jadeite. The stone was inert to longwave ultraviolet radiation. Magnification did not reveal any evidence of treatment. As is often the case with purple jadeite, the origin of the color could be be determined.
Infrared spectroscopy
The spectrum of this stone reveals intense absorptions around 2900cm¯¹ which are not found in natural jadeite. These additional features are due to the presence of an ‘opticon-like’ polymer. This is not surprising, since this type of polymer is the most commonly employed for jadeite impregnation, according to many reports and our own experience.
Discussion
This finding is particularly significant since none of the polymer-impregnated jadeite (or B jade) we have seen so far was purple in color. They have all been green or mottled green and white, some with applied spots of brown. This means that we will now have to expand our routine testing for polymer impregnation to include purple jadeites as well.
New polymers for jadeite impregnation
We have recently encountered two new types of polymer used for the treatment of jadeite, in addition to the three previously described which are wax, an ‘opticon-like’ polymer, and phthalate-like polymer. Since we do not know yet their exact nature, we will refer to them as polymer 4 and polymer 5.
Polymer 4
The infrared spectrum of polymer 4 is very similar—but not identical—to that of wax. In particular, the major absorption is slightly shifted and of different width than that for wax. Jadeites treated with this product do not ‘sweat’ when tested with the thermal reaction tester, as opposed to those impregnated with wax which do. We measured the SG of one stone showing this kind of impregnation at 3.33.
Polymer 5
The infrared spectrum of polymer 5 shows similar absorption features as polymer 4, plus five more in the range of 2950-3150 cm¯¹. The three jadeites impregnated with this material that we studied are inert in ultraviolet radiation. We could measure the SG on only one of them, and the stone floated in the 3.32 SG liquid (methylene iodide). It is interesting to note that two of these stones displayed ‘sweating’ when tested with T.R.T.
Conclusion
These two new polymers have been seen on a few jadeites submitted for identification, and laboratories involved in B-jade detection should be aware of them. They demonstrate the growing variety of polymers that are being used for jade treatment. One reason for this could be the increasing number of companies involved in this treatment.
Yellow And Orange Sapphires
(via ICA Lab Alert, No.1, June 2, 1987) AIGS writes:
Background
In 1981, we at AIGS were asked to identify what was undoubtedly among the first heat treated Sri Lankan yellows to come out of ovens of Bangkok. We were told that the stone was treated by an unknown process (which was later found to be heat), and were asked to determine the color stability. This we proceeded to do by performing our usual fade test. This consisted of exposing the stone to heat and light at 1cm distance of a 150 watt spotlight for up to one hour. We were truly surprised when, after a few minutes exposure, the color had become much darker and more brownish (stones treated with irradiation would fade; some untreated Sri Lankan yellows will fade, but in most the color will not change). This change was temporary only; as the stone cooled to room temperature the color returned to normal.
Since this time we have tested over a thousand Sri Lankan yellow/orange sapphires and have found that all of the heat treated yellow to orange stones react in this way. Thus, a simple test for detection of heat treatment in Sri Lankan yellow/orange sapphires is possible.
The test
Place the stone in close proximetry to a source of mild source of heat, such as an incandescent bulb.
Results
Heat treated Sri Lankan yellow/orange sapphire —The color darkens temporarily, becoming more brownish. The deeper the original color, the greater the change. As the stone cools, the color returns to its original state. Control stones should be used so as to detect even slight changes in color.
Irradiated Sri Lankan yellow/orange sapphire —The color will fade, usually within one hour.
Untreated Sri Lankan yellow/orange sapphire —Generally no change, however some stones may show some fading.
Thai/Australian yellow/orange sapphire, heat treated or untreated—no change has been observed in the color of these stones.
(To: Mr N Horiuchi; Subject: Response to comment on Lab Alert No.1) AIGS writes:
Discussion
Mr N Horiuchi has commented on the test we previously described in Lab Alert No.1 to detect heat treatment in Sri Lankan yellow/orange sapphires. Mr Horiuchi stated that this color also did not fade under the same condition as reported on (by) AIGS.
From the above statement it appears that Mr Horiuchi has not understood the text of Lab Alert No.1. As others may also have misunderstood the text, we will describe the test again below.
Heat treatment in Sri Lankan yellow to orange sapphires may be detected by applying a simple fade test. (Caution: This test only works for Sri Lankan stones). Once a yellow/orange sapphire has been identified as definitely originating from Sri Lanka, its color is tested by applying a simple fade test. The stone in question should be placed on a glass (or other nonflammable) platform within ½ cm of a hot 150 watt (or more) spotlight. The idea is to expose the stone to lots of light and heat. After about 15 minutes exposure (as the stone heats up), the color of a heat treated yellow/orange sapphire will have been found to have become slightly darker and more brownish (the deeper the starting color before the test, the deeper and more brownish the color after heating up). This change is temporary only. As the stone cools its color will fade back to the color before the test was started, not, we repeat, not back to the color before the stone was heat treated (by someone else presumably). We believe that is where Mr Horiuchi misunderstood the original Lab Alert.
Other possible reactions
If the stone has been irradiated (either by nature or by man) the color will fade, usually within one hour’s exposure. In most natural Sri Lankan sapphires, however, the color will show no change. Natural yellow/orange sapphires from other sources and synthetic yellow/orange sapphires also show no change.
To make this test more accurate, control stones of similar color to the stone being tested should be used. Then after the stone in question heats up it can be compared to the color of the control stone. In the case of heat treated yellow/orange Sri Lankan sapphires, the change is not subtle in deeply colored stones, and anyone with normal vision should easily detect it, but the comparison must be made quickly before the stone tested cools down.
Dr Kurt Nassau has informed us that under certain conditions, yellow/orange sapphires may get darker upon exposure to some kinds of visible light. We have absolutely no information on exactly what kinds of stones do this or under what conditions. However he has promised us that the subject will be described in detail soon in an article he has written for Gems & Gemology. We have also written an article on the subjects covered in Lab Alerts Nos. 1 and 2 and submitted it to Gems & Gemology. We don’t know when it will appear (or if it will appear). We have had no reply of any kind, even though we sent it 8 weeks ago.
The subject of color in yellow sapphires is extremely complex. We have no illusions that the above information is the last word on the subject. However, over the past ten years we have tested thousands of pieces of yellow/orange sapphire from all sources and this is what we have found. If anyone else could she additional light on the subject, we would love to hear from them.
Dr K Schmetzer replies:
A. Fe³+ or by Fe³+ and Ti³+: Type 1, originating from Nigeria, Thailand, Australia or
B. By a yellow color center: Type 2, originating from Sri Lanka.
By heat or irradiation heat treatment, yellow stones with similar color centers, i.e with absorption spectrum similar to the spectrum of Type 2, but with different stabilities to light or heat are produced.
C. Irradiation treatment, color center: Type 3
D. Heat treatment, color center: Type 4
According to my experience and knowledge, AIGS describes a test for Type 4 stones, and N Horiuchi is dealing with Type 3 stones. Dr Nassau describes Type 2 stones in Alert No.9, and this type of yellow color center may be connected with natural irradiation. The reason for the higher stability of this naturally irradiated yellow compared to artificially irradiated yellow is an unknown but similar results were found by myself with natural irradiated yellow quartz (citrine) and artificially irradiated yellow quartz.
Background
In 1981, we at AIGS were asked to identify what was undoubtedly among the first heat treated Sri Lankan yellows to come out of ovens of Bangkok. We were told that the stone was treated by an unknown process (which was later found to be heat), and were asked to determine the color stability. This we proceeded to do by performing our usual fade test. This consisted of exposing the stone to heat and light at 1cm distance of a 150 watt spotlight for up to one hour. We were truly surprised when, after a few minutes exposure, the color had become much darker and more brownish (stones treated with irradiation would fade; some untreated Sri Lankan yellows will fade, but in most the color will not change). This change was temporary only; as the stone cooled to room temperature the color returned to normal.
Since this time we have tested over a thousand Sri Lankan yellow/orange sapphires and have found that all of the heat treated yellow to orange stones react in this way. Thus, a simple test for detection of heat treatment in Sri Lankan yellow/orange sapphires is possible.
The test
Place the stone in close proximetry to a source of mild source of heat, such as an incandescent bulb.
Results
Heat treated Sri Lankan yellow/orange sapphire —The color darkens temporarily, becoming more brownish. The deeper the original color, the greater the change. As the stone cools, the color returns to its original state. Control stones should be used so as to detect even slight changes in color.
Irradiated Sri Lankan yellow/orange sapphire —The color will fade, usually within one hour.
Untreated Sri Lankan yellow/orange sapphire —Generally no change, however some stones may show some fading.
Thai/Australian yellow/orange sapphire, heat treated or untreated—no change has been observed in the color of these stones.
(To: Mr N Horiuchi; Subject: Response to comment on Lab Alert No.1) AIGS writes:
Discussion
Mr N Horiuchi has commented on the test we previously described in Lab Alert No.1 to detect heat treatment in Sri Lankan yellow/orange sapphires. Mr Horiuchi stated that this color also did not fade under the same condition as reported on (by) AIGS.
From the above statement it appears that Mr Horiuchi has not understood the text of Lab Alert No.1. As others may also have misunderstood the text, we will describe the test again below.
Heat treatment in Sri Lankan yellow to orange sapphires may be detected by applying a simple fade test. (Caution: This test only works for Sri Lankan stones). Once a yellow/orange sapphire has been identified as definitely originating from Sri Lanka, its color is tested by applying a simple fade test. The stone in question should be placed on a glass (or other nonflammable) platform within ½ cm of a hot 150 watt (or more) spotlight. The idea is to expose the stone to lots of light and heat. After about 15 minutes exposure (as the stone heats up), the color of a heat treated yellow/orange sapphire will have been found to have become slightly darker and more brownish (the deeper the starting color before the test, the deeper and more brownish the color after heating up). This change is temporary only. As the stone cools its color will fade back to the color before the test was started, not, we repeat, not back to the color before the stone was heat treated (by someone else presumably). We believe that is where Mr Horiuchi misunderstood the original Lab Alert.
Other possible reactions
If the stone has been irradiated (either by nature or by man) the color will fade, usually within one hour’s exposure. In most natural Sri Lankan sapphires, however, the color will show no change. Natural yellow/orange sapphires from other sources and synthetic yellow/orange sapphires also show no change.
To make this test more accurate, control stones of similar color to the stone being tested should be used. Then after the stone in question heats up it can be compared to the color of the control stone. In the case of heat treated yellow/orange Sri Lankan sapphires, the change is not subtle in deeply colored stones, and anyone with normal vision should easily detect it, but the comparison must be made quickly before the stone tested cools down.
Dr Kurt Nassau has informed us that under certain conditions, yellow/orange sapphires may get darker upon exposure to some kinds of visible light. We have absolutely no information on exactly what kinds of stones do this or under what conditions. However he has promised us that the subject will be described in detail soon in an article he has written for Gems & Gemology. We have also written an article on the subjects covered in Lab Alerts Nos. 1 and 2 and submitted it to Gems & Gemology. We don’t know when it will appear (or if it will appear). We have had no reply of any kind, even though we sent it 8 weeks ago.
The subject of color in yellow sapphires is extremely complex. We have no illusions that the above information is the last word on the subject. However, over the past ten years we have tested thousands of pieces of yellow/orange sapphire from all sources and this is what we have found. If anyone else could she additional light on the subject, we would love to hear from them.
Dr K Schmetzer replies:
A. Fe³+ or by Fe³+ and Ti³+: Type 1, originating from Nigeria, Thailand, Australia or
B. By a yellow color center: Type 2, originating from Sri Lanka.
By heat or irradiation heat treatment, yellow stones with similar color centers, i.e with absorption spectrum similar to the spectrum of Type 2, but with different stabilities to light or heat are produced.
C. Irradiation treatment, color center: Type 3
D. Heat treatment, color center: Type 4
According to my experience and knowledge, AIGS describes a test for Type 4 stones, and N Horiuchi is dealing with Type 3 stones. Dr Nassau describes Type 2 stones in Alert No.9, and this type of yellow color center may be connected with natural irradiation. The reason for the higher stability of this naturally irradiated yellow compared to artificially irradiated yellow is an unknown but similar results were found by myself with natural irradiated yellow quartz (citrine) and artificially irradiated yellow quartz.
Unusual Composite Ruby
(via ICA Lab Alert, No.2, June 1987) AIGS writes:
During June of 1987, a very unusual composite ruby/synthetic ruby was brought in to the lab of AIGS for testing. It consisted of a piece of Verneuil synthetic ruby to which had been joined at the edge a smaller chunk of natural Burmese ruby. The whole stone was then faceted, concealing the join.
Two features are unusual about this stone. First of all, what appears to be glass has been used to join the two together. Gas bubbles were found in the glass area. Secondly, the edges of both the natural and synthetic areas were irregular. The use of glass to join the two together made this possible, as the glass-filled in the irregular surfaces. The entire stone showed signs of heat treatment, with induced fingerprints present in the synthetic section.
Detection
With the loupe or naked eye this stone could fool many people as the join looks like a crack and the natural area contained a large cloud of silk. However, immersion or overhead lighting will reveal the different luster of the glass join in the microscope. In addition, the synthetic portion displays curved striae and gas bubbles, as well as the induced fingerprints. The stone was purposely cut ‘native’ to imitate the appearance of a ruby just brought out from Burma.
During June of 1987, a very unusual composite ruby/synthetic ruby was brought in to the lab of AIGS for testing. It consisted of a piece of Verneuil synthetic ruby to which had been joined at the edge a smaller chunk of natural Burmese ruby. The whole stone was then faceted, concealing the join.
Two features are unusual about this stone. First of all, what appears to be glass has been used to join the two together. Gas bubbles were found in the glass area. Secondly, the edges of both the natural and synthetic areas were irregular. The use of glass to join the two together made this possible, as the glass-filled in the irregular surfaces. The entire stone showed signs of heat treatment, with induced fingerprints present in the synthetic section.
Detection
With the loupe or naked eye this stone could fool many people as the join looks like a crack and the natural area contained a large cloud of silk. However, immersion or overhead lighting will reveal the different luster of the glass join in the microscope. In addition, the synthetic portion displays curved striae and gas bubbles, as well as the induced fingerprints. The stone was purposely cut ‘native’ to imitate the appearance of a ruby just brought out from Burma.
Plastic Coating Of Gemstones
(via ICA Lab Alert, No.3, 1987) AIGS writes:
Details
In the past 3 years, gemologists at AIGS in Bangkok have encountered an unusual type of assembled stone in which an inferior specimen is coated with colored plastic. All of the stones treated in this manner have been of Burmese origin and so it is believed that the treatment is probably done in Burma.
One type consists of a poor color jadeite cabochon coated with a thin layer of rich green plastic. The coating covers all surfaces of the cabochon except the bottom. After coating, the stone appears to be of very high quality.
Another type is a light color faceted ruby coated with red plastic and then repolished. This gives the appearance of a fine ruby.
The third type seen is a white star sapphire cabochon entirely coated with red plastic. The gem then appears like a beautiful star ruby.
Detection
Although extremely deceptive to the naked eye, these plastic coated stones are readily identified under magnification. They may be dangerous to the trade, though, because their appearance is so natural that unsuspecting dealer might not even check them with the loupe. One unaided clue is provided by the slightly warm and plastic-like feel of the stones. This, however, is very subtle.
Identification of plastic coating is made with the microscope. In the case of the jadeite, as the plastic does not cover the stone entirely, it may be seen to peel away from the stone in places along the girdle. In all types, gas bubbles may be visible in the plastic coating, particularly in the star ruby type, where the coating was thicker. Color swirls could also be seen in the star ruby type. Judicious use of the hot point will, of course, also reveal this fraud.
Details
In the past 3 years, gemologists at AIGS in Bangkok have encountered an unusual type of assembled stone in which an inferior specimen is coated with colored plastic. All of the stones treated in this manner have been of Burmese origin and so it is believed that the treatment is probably done in Burma.
One type consists of a poor color jadeite cabochon coated with a thin layer of rich green plastic. The coating covers all surfaces of the cabochon except the bottom. After coating, the stone appears to be of very high quality.
Another type is a light color faceted ruby coated with red plastic and then repolished. This gives the appearance of a fine ruby.
The third type seen is a white star sapphire cabochon entirely coated with red plastic. The gem then appears like a beautiful star ruby.
Detection
Although extremely deceptive to the naked eye, these plastic coated stones are readily identified under magnification. They may be dangerous to the trade, though, because their appearance is so natural that unsuspecting dealer might not even check them with the loupe. One unaided clue is provided by the slightly warm and plastic-like feel of the stones. This, however, is very subtle.
Identification of plastic coating is made with the microscope. In the case of the jadeite, as the plastic does not cover the stone entirely, it may be seen to peel away from the stone in places along the girdle. In all types, gas bubbles may be visible in the plastic coating, particularly in the star ruby type, where the coating was thicker. Color swirls could also be seen in the star ruby type. Judicious use of the hot point will, of course, also reveal this fraud.
Glass Infilling Of Cracks In Ruby
(via ICA Lab Alert, No. 4, June, 1987) AIGS writes:
Details
During the ICA Congress held recently in Bangkok, Dr Henri Hanni of Switzerland described to us a new ruby treatment. This consisted of poor quality African ruby cabochons whose cracks had been filled with glass. At the time of the Congress we had not yet seen these stones in Bangkok. In late June of 1987 we saw the first stone. It was a heavily included ruby cabochon, with many cracks that passed deep into the stone. These were filled with glass-like substance. This treatment differs from ordinary surface repaired rubies as the glass dos not just fill in surface pits, but instead appears to penetrate deep into the cracks.
Detection
This treatment is easily detected in the same manner as ordinary surface repaired rubies. Using overhead lighting, or immersion in methylene iodide, will reveal the glass filling due to its different luster or relief. If the opening of the crack is very narrow, however, the glass filling may be difficult to see. Gas bubbles may be found in some of the glass areas.
Dr K Schmetzer writes:
Kenyan rubies are also treated with plastics in order to improve the quality of the stones. In the treatment, cracks or fissures were filled with plastics which is sometimes deeply penetrating into the stones.
Details
During the ICA Congress held recently in Bangkok, Dr Henri Hanni of Switzerland described to us a new ruby treatment. This consisted of poor quality African ruby cabochons whose cracks had been filled with glass. At the time of the Congress we had not yet seen these stones in Bangkok. In late June of 1987 we saw the first stone. It was a heavily included ruby cabochon, with many cracks that passed deep into the stone. These were filled with glass-like substance. This treatment differs from ordinary surface repaired rubies as the glass dos not just fill in surface pits, but instead appears to penetrate deep into the cracks.
Detection
This treatment is easily detected in the same manner as ordinary surface repaired rubies. Using overhead lighting, or immersion in methylene iodide, will reveal the glass filling due to its different luster or relief. If the opening of the crack is very narrow, however, the glass filling may be difficult to see. Gas bubbles may be found in some of the glass areas.
Dr K Schmetzer writes:
Kenyan rubies are also treated with plastics in order to improve the quality of the stones. In the treatment, cracks or fissures were filled with plastics which is sometimes deeply penetrating into the stones.
Friday, April 20, 2007
Natural And Synthetic Yellow/Orange Sapphires
(via ICA Lab Alert, No. 5, December 1987) AIGS writes:
Subject
The detection of color banding/growth zoning in natural and synthetic yellow/orange sapphires.
Method
Color banding, either straight or curved, can be detected much more easily by using a technique developed at AIGS in 1981. This involves the use of a frosted (diffused) blue filter over the microscope’s light source.
When looking for color zoning in yellow sapphires, the usual practice is to immerse the stone in methylene iodide. However, with a yellow stone in a yellow liquid over a yellow (incandescent) light, there is little chance of finding yellow bands of color. Using a white (fluorescent) light helps a bit, but not enough. AIGS have found that by using a frosted blue filter it becomes a much more easier to locate color bands, either straight or curved, as blue is the color being absorbed the most in yellow stones. Sometimes we stack two or three blue filters on top of one another. Although this does not cut down on the light intensity, it still makes it much easier to locate the color zoning. Using the frosted blue filter plus immersion, it is possible to locate straight or curved color banding in about 95% or more of all natural and synthetic yellow/orange sapphires. Furthermore, a green filter can be used for rubies—the color of the should approximate the absorption maxima of the stone.
E Gubelin writes:
To use a frosted blue filter and examine the gem in immersion is an excellent suggestion (though known to experienced gemologist for many years already). The effect may be enhanced if one close the diaphragm to about half or about a quarter of its diameter below the immersion cell.
Subject
The detection of color banding/growth zoning in natural and synthetic yellow/orange sapphires.
Method
Color banding, either straight or curved, can be detected much more easily by using a technique developed at AIGS in 1981. This involves the use of a frosted (diffused) blue filter over the microscope’s light source.
When looking for color zoning in yellow sapphires, the usual practice is to immerse the stone in methylene iodide. However, with a yellow stone in a yellow liquid over a yellow (incandescent) light, there is little chance of finding yellow bands of color. Using a white (fluorescent) light helps a bit, but not enough. AIGS have found that by using a frosted blue filter it becomes a much more easier to locate color bands, either straight or curved, as blue is the color being absorbed the most in yellow stones. Sometimes we stack two or three blue filters on top of one another. Although this does not cut down on the light intensity, it still makes it much easier to locate the color zoning. Using the frosted blue filter plus immersion, it is possible to locate straight or curved color banding in about 95% or more of all natural and synthetic yellow/orange sapphires. Furthermore, a green filter can be used for rubies—the color of the should approximate the absorption maxima of the stone.
E Gubelin writes:
To use a frosted blue filter and examine the gem in immersion is an excellent suggestion (though known to experienced gemologist for many years already). The effect may be enhanced if one close the diaphragm to about half or about a quarter of its diameter below the immersion cell.
Plastic Treated Emeralds
(via ICA Lab Alert No. 6, August 13, 1987) Nubio Horiuchi writes:
Source
I have personally seen this treatment for the past three years in Japan (Central Gem Laboratory).
Status
Details of this have not been announced yet, but it is summarized as follows:
The fractures are first cleaned and then impregnated with some kind of liquid plastic. It is presumed that the liquid plastic is hardened by irradiation of light or ultraviolet rays.
Merit of this treatment
In normal oil treatment the oil will seep out during cleaning or over a period of normal wearing and there is a gradual loss of color and the fractures become noticeable. However, with the impregnation of liquid plastic the treatment is durable.It would appear from the durability standpoint that the liquid plastic treatment is better than oiling.
Identification
It is difficult to distinguish between oil and plastic treatments.
Question
In which category of enhancement and treatment should the plastic treated emeralds be classified?
E. Gubelin writes:
Though more durable the result of this new plastic treatment should become to known to all members immediately, because many members of the trade use an ultrasonic cleaning machine which causes the oil to be washed out. If no oil is being washed out, people might not become aware of the fact that the fractures are filled with plastic films. Despite the greater durability the stimulus for easier fraudulent practices does by no ways raise the ethical standard of this plastic treatment.
Dr K Schmetzer writes:
The stones should be classified as plastic-impregnated emeralds.
Source
I have personally seen this treatment for the past three years in Japan (Central Gem Laboratory).
Status
Details of this have not been announced yet, but it is summarized as follows:
The fractures are first cleaned and then impregnated with some kind of liquid plastic. It is presumed that the liquid plastic is hardened by irradiation of light or ultraviolet rays.
Merit of this treatment
In normal oil treatment the oil will seep out during cleaning or over a period of normal wearing and there is a gradual loss of color and the fractures become noticeable. However, with the impregnation of liquid plastic the treatment is durable.It would appear from the durability standpoint that the liquid plastic treatment is better than oiling.
Identification
It is difficult to distinguish between oil and plastic treatments.
Question
In which category of enhancement and treatment should the plastic treated emeralds be classified?
E. Gubelin writes:
Though more durable the result of this new plastic treatment should become to known to all members immediately, because many members of the trade use an ultrasonic cleaning machine which causes the oil to be washed out. If no oil is being washed out, people might not become aware of the fact that the fractures are filled with plastic films. Despite the greater durability the stimulus for easier fraudulent practices does by no ways raise the ethical standard of this plastic treatment.
Dr K Schmetzer writes:
The stones should be classified as plastic-impregnated emeralds.
New Treatment For Diamonds
(via ICA Lab Alert No.7, August 13, 1987) Nubo Horiuchi writes:
Source
I found this treatment in January 1987.
Status
This treatment makes cleavage cracks to the surface less visible by impregnating with unknown material. On looking through the cleavage crack of a diamond treated in this manner, a whitish appearance can be seen which improves the clarity grade of the diamond. Impregnating the cleavage crack of the diamond with this unknown material, which may be silicon oil, it is quite effective in improving the appearance of the cleavage crack because it reduces diffuse reflections. This treatment was located in the diamonds lots imported from Israel.
Identification
Upon looking through a diamond under a diamond light, a dark blue or rainbow hue of interference color will be seen under the diffused light.
Opinion
The organization of gem laboratories in Japan judges that diamonds enhanced in this manner are treated diamonds.
E.Gubelin writes:
It certainly is imperative that all members are informed about this new unethical treatment of diamonds because too many dealers might consider these artificially filled fractures as naturally lined fissures.
Youichi Horikawa writes:
I think identification of these treated diamonds is not easy, because the interference color can be seen in untreated diamonds also.
Source
I found this treatment in January 1987.
Status
This treatment makes cleavage cracks to the surface less visible by impregnating with unknown material. On looking through the cleavage crack of a diamond treated in this manner, a whitish appearance can be seen which improves the clarity grade of the diamond. Impregnating the cleavage crack of the diamond with this unknown material, which may be silicon oil, it is quite effective in improving the appearance of the cleavage crack because it reduces diffuse reflections. This treatment was located in the diamonds lots imported from Israel.
Identification
Upon looking through a diamond under a diamond light, a dark blue or rainbow hue of interference color will be seen under the diffused light.
Opinion
The organization of gem laboratories in Japan judges that diamonds enhanced in this manner are treated diamonds.
E.Gubelin writes:
It certainly is imperative that all members are informed about this new unethical treatment of diamonds because too many dealers might consider these artificially filled fractures as naturally lined fissures.
Youichi Horikawa writes:
I think identification of these treated diamonds is not easy, because the interference color can be seen in untreated diamonds also.
New Diamond Treatment
(via ICA Lab Alert No.8, August 14, 1987) GIA GTL writes:
The New York GIA GTL recently examined a group of diamonds which had undergone a ‘fill’ treatment to improve their appearance.
‘We were told the diamonds had been treated in Israel and that this process has been in use for some time,” said Bert Krashes. “In view of the obligation of the jeweler to disclose treatments, this procedure will be yet another challenge in terminology and explanation to the retail customer.”
Apparently, the treatment has been applied only to highly imperfect diamonds with flaws that open to the surface. By introducing a high refractive index fill into fractures and gletzes, they become dramatically less noticeable to the unaided eye. I2 and I3 grades, for example, are improved to an I1 appearance.
Under binocular magnification, the appearance of these cracks is different from untreated ones, showing white thread-like and pinpoint deposits similar to ‘fingerprint’ inclusions. In addition, an orangy brown reflection was observed in the surfaces reached by the cracks. This suggests the color of the filler used may be brownish, typical of high refractive liquids. It has been reported that the filler can be removed by soaking in aqua regia. The treatment is said to now be available in Antwerp as well as Israel.
“The examination was necessarily hurried and only a few diamonds were available to us; therefore this should be considered an alert rather than a definitive description,” said Krashes. “GIA is attempting to secure more of these diamonds for study and will issue a full report as soon as possible.”
The New York GIA GTL recently examined a group of diamonds which had undergone a ‘fill’ treatment to improve their appearance.
‘We were told the diamonds had been treated in Israel and that this process has been in use for some time,” said Bert Krashes. “In view of the obligation of the jeweler to disclose treatments, this procedure will be yet another challenge in terminology and explanation to the retail customer.”
Apparently, the treatment has been applied only to highly imperfect diamonds with flaws that open to the surface. By introducing a high refractive index fill into fractures and gletzes, they become dramatically less noticeable to the unaided eye. I2 and I3 grades, for example, are improved to an I1 appearance.
Under binocular magnification, the appearance of these cracks is different from untreated ones, showing white thread-like and pinpoint deposits similar to ‘fingerprint’ inclusions. In addition, an orangy brown reflection was observed in the surfaces reached by the cracks. This suggests the color of the filler used may be brownish, typical of high refractive liquids. It has been reported that the filler can be removed by soaking in aqua regia. The treatment is said to now be available in Antwerp as well as Israel.
“The examination was necessarily hurried and only a few diamonds were available to us; therefore this should be considered an alert rather than a definitive description,” said Krashes. “GIA is attempting to secure more of these diamonds for study and will issue a full report as soon as possible.”
Yellow Sapphire
(via ICA Lab Alert, No.9, September 1, 1987) Kurt Nassau writes:
Background
There are several types of natural yellow sapphires that are seen in the trade, including the untreated, the high temperature heated, and the irradiated ones. The first two are stable to light, while the third (irradiated either by nature or by man) fades in light. Natural yellow stones after being mined may fade on light exposure, and it is customary to expose such material to light or heat it. A heating test is also sometimes used to check yellow sapphire for fading: Webster recommends 230°C (446°F) for a few minutes and Nassau has used 200°C for one hour to establish a potential for fading in light in irradiated gemstones in general.
Observation
Ordinary yellow sapphire, that is the non-irradiated, non-heated, non-light fading, stable material can lose some color at as low as 60°C (140°F), more at higher temperatures, and all color by 600°C (1112°F). Quite unexpectedly, light has been found to reverse this change. It restores this type of yellow sapphire to its ‘proper’ stable color from either the dark irradiated state or from the lighter heated state. If heating has been performed accidentally, the color may be restored by exposure to bright light for a few days.
Recommendations
Do not use a heating test for any yellow sapphire. To test for irradiated stones, a light exposure test is the only one that can safely be recommended.
Reference
A fully detailed article by Kurt Nassau and G Kay Valente has been submitted for publication in Gems & Gemology under the title “The Seven Types of Yellow Sapphire and a Corundum Conurundum.”
Background
There are several types of natural yellow sapphires that are seen in the trade, including the untreated, the high temperature heated, and the irradiated ones. The first two are stable to light, while the third (irradiated either by nature or by man) fades in light. Natural yellow stones after being mined may fade on light exposure, and it is customary to expose such material to light or heat it. A heating test is also sometimes used to check yellow sapphire for fading: Webster recommends 230°C (446°F) for a few minutes and Nassau has used 200°C for one hour to establish a potential for fading in light in irradiated gemstones in general.
Observation
Ordinary yellow sapphire, that is the non-irradiated, non-heated, non-light fading, stable material can lose some color at as low as 60°C (140°F), more at higher temperatures, and all color by 600°C (1112°F). Quite unexpectedly, light has been found to reverse this change. It restores this type of yellow sapphire to its ‘proper’ stable color from either the dark irradiated state or from the lighter heated state. If heating has been performed accidentally, the color may be restored by exposure to bright light for a few days.
Recommendations
Do not use a heating test for any yellow sapphire. To test for irradiated stones, a light exposure test is the only one that can safely be recommended.
Reference
A fully detailed article by Kurt Nassau and G Kay Valente has been submitted for publication in Gems & Gemology under the title “The Seven Types of Yellow Sapphire and a Corundum Conurundum.”
Diamond Films
(via ICA Lab Alert, No.10, September 1, 1987) Kurt Nassau writes:
Status
Much publicity both in the general press as well as in the trade has recently been focused on thin diamond films grown by a variety of low pressure techniques. Most of this publicity is highly exaggerated.
The facts are the following:
- Thin films of single crystal diamond can be grown on diamond, but the growth rate is so extremely slow that this is of no significance to the gemstone field.
- Thin films of polycrystalline diamond, composed of many tiny crystals, can be grown quite rapidly on a variety of surfaces, but adhesion is mostly very poor. Since such films are not single crystal, their presence should be easier to detect than most other coatings on gemstones. They could only fool a thermal diamond tester if the coating is very thick, when their presence should be immediately evident under the loupe.
Reference
More detail is given in an article being published in Jeweler’s Circular Keystone under the title “New Synthetics: Cause for Panic—or for the Blahs?”
Status
Much publicity both in the general press as well as in the trade has recently been focused on thin diamond films grown by a variety of low pressure techniques. Most of this publicity is highly exaggerated.
The facts are the following:
- Thin films of single crystal diamond can be grown on diamond, but the growth rate is so extremely slow that this is of no significance to the gemstone field.
- Thin films of polycrystalline diamond, composed of many tiny crystals, can be grown quite rapidly on a variety of surfaces, but adhesion is mostly very poor. Since such films are not single crystal, their presence should be easier to detect than most other coatings on gemstones. They could only fool a thermal diamond tester if the coating is very thick, when their presence should be immediately evident under the loupe.
Reference
More detail is given in an article being published in Jeweler’s Circular Keystone under the title “New Synthetics: Cause for Panic—or for the Blahs?”
New Synthetic Alexandrite
(via ICA Lab Alert, No.11, September 1, 1987) Kurt Nassau writes:
Background
In 1976 U.S patent 3,997,853 by R C Morris and C F Cline was assigned to Allied Chemical Corp. This described the Czochralski growth pulling from the melt of alexandrite (chrysoberyl containing chromium and showing a color change). The patent discussed the laser use of such crystals containing only low levels of chromium that produce only a weak alexandrite effect. This matter was covered in my book “Gems Made by Man”.
Status
Higher concentrations of chromium, that give a very good alexandrite effect in very clean material, is now being grown by the Czochralski technique of pulling from the melt by Allied and is about to be marketed by M S B Industries Inc of Hillside, New Jersey. Gemological examination by the author and the GIA is under way and the characteristics of Czochralski grown synthetic alexandrite will be published when the work has been completed. This material can be expected to appear in the trade soon.
Background
In 1976 U.S patent 3,997,853 by R C Morris and C F Cline was assigned to Allied Chemical Corp. This described the Czochralski growth pulling from the melt of alexandrite (chrysoberyl containing chromium and showing a color change). The patent discussed the laser use of such crystals containing only low levels of chromium that produce only a weak alexandrite effect. This matter was covered in my book “Gems Made by Man”.
Status
Higher concentrations of chromium, that give a very good alexandrite effect in very clean material, is now being grown by the Czochralski technique of pulling from the melt by Allied and is about to be marketed by M S B Industries Inc of Hillside, New Jersey. Gemological examination by the author and the GIA is under way and the characteristics of Czochralski grown synthetic alexandrite will be published when the work has been completed. This material can be expected to appear in the trade soon.
Reappearance Of Surface Diffusion Treated Blue Sapphires in Bangkok
(via ICA Lab Alert, No.12, October 21, 1987) AIGS writes:
Discussion
Most gemologists are well aware of the surface diffusion treatment for corundums. A light colored stone is packed in a slurry of coloring agents and heated to near the melting point. This drives the coloring agents just beneath the surface, creating a deeply colored skin. The stone is then lightly repolished.
In the early 1980s many such stones were seen in Bangkok, usually of a blue color, and some stone burners performed the treatment locally. However it seemed that after unscrupulous dealers learned that gemologists could easily spot the treatment, the incentive was gone and such stones largely disappeared from the market. At least they did until this week. Then several stones came to AIGS for testing which had been treated in this way. They differed from those seen in the past in that they were not near colorless stones coated to a deep blue. By skillful repolishing most of the coating was removed, leaving just enough to improve the stone a bit. In other words, the coating made a $100/ct, sapphire into a $150/ct stone. In the past week we have seen over five of these stones. We suspect that one or more local burners may be performing the treatment.
Identification
These stones are much more difficult to identify because most of the surface coating has been removed by careful repolishing, and because the stones do contain a fair amount of naturally occurring color banding inside the stone. Identification may be made, however, by examining the girdle region and facet junctions very carefully under immersion cell. Interestingly enough, horizontal microscopes do not work as well as the Gem Instrument’s ‘Gemolite’ because the light on horizontal microscopes comes from one side only, while in Gemolite the light comes from all directions due to a circular glass diffusing ring. Identifying these diffusion treated stones is made best by careful examination of the stone’s surface under immersion. Color will be found in places to follow the facets, which is impossible in an untreated stone. Again, confusion is easy however, because these stones may contain considerable natural color within the stone. Side-by-side comparison with a known natural stone and a known surface diffusion treated stone will aid in making difficult separations.
Discussion
Most gemologists are well aware of the surface diffusion treatment for corundums. A light colored stone is packed in a slurry of coloring agents and heated to near the melting point. This drives the coloring agents just beneath the surface, creating a deeply colored skin. The stone is then lightly repolished.
In the early 1980s many such stones were seen in Bangkok, usually of a blue color, and some stone burners performed the treatment locally. However it seemed that after unscrupulous dealers learned that gemologists could easily spot the treatment, the incentive was gone and such stones largely disappeared from the market. At least they did until this week. Then several stones came to AIGS for testing which had been treated in this way. They differed from those seen in the past in that they were not near colorless stones coated to a deep blue. By skillful repolishing most of the coating was removed, leaving just enough to improve the stone a bit. In other words, the coating made a $100/ct, sapphire into a $150/ct stone. In the past week we have seen over five of these stones. We suspect that one or more local burners may be performing the treatment.
Identification
These stones are much more difficult to identify because most of the surface coating has been removed by careful repolishing, and because the stones do contain a fair amount of naturally occurring color banding inside the stone. Identification may be made, however, by examining the girdle region and facet junctions very carefully under immersion cell. Interestingly enough, horizontal microscopes do not work as well as the Gem Instrument’s ‘Gemolite’ because the light on horizontal microscopes comes from one side only, while in Gemolite the light comes from all directions due to a circular glass diffusing ring. Identifying these diffusion treated stones is made best by careful examination of the stone’s surface under immersion. Color will be found in places to follow the facets, which is impossible in an untreated stone. Again, confusion is easy however, because these stones may contain considerable natural color within the stone. Side-by-side comparison with a known natural stone and a known surface diffusion treated stone will aid in making difficult separations.
Characteristics Of Heat Treated And Diffusion Treated Corundums
(1982) Henry A Hanni writes:
For the past two years blue sapphires with good color and pleasing size have become more abundant in the trade. Surprisingly, these stones are offered in lots in which the individual stones are uniformly colored. This is not common with larger gems of high value. Initially, we dealt with such sapphires very carefully and objectively due to a vague suspicion.
During the course of our investigation (Bosshart 1981) the subject of heat treatment of corundum has been brought up at various international meetings of gemologists. Finally, Nassau, Crowningshield and Liddicoat went public with some presentations, which if not quite complete are fairly comprehensive. This report is supplementary state of the author to a recent publication (Hanni 1982).
Heat treatment of corundum has long been practiced, on the one hand after indigenous methods in the countries of origin (i.e. Sri Lanka), on the other hand after an industrial method employed since 1973. With local methods, controlling of temperature and environment is not satisfactorily possible. Because of this, the results are unreliable. Application of the industrial method, carried out in the USA and Thailand, guarantees constant, controlled conditions and leads to the desired results. Let us consider the patents of Union Carbide in 1973 as a starting point. In these patents, techniques are described which allow (at first applied to synthetics only) a homogenization or improvement of the color or the development of asterism. Over the last years, these processes have been tried and improved on natural corundum. Presently, masters of such techniques reside in Thailand. Their latest surprising creations are yellow to orange corundums produced by heat treating raw material corundum of an as yet undescribed type.
The aim of heat treatment is to reach a uniform distribution of color, to clarify or to increase the color, or to attain better purity by dissolving certain inclusions. Critical is whether these stones have absorbed foreign matter during the process of heat treatment, or the required improvement was achieved with those components already present in the stone. Recently, Dr Nassau has reviewed the different processes (Nassau 1981, tab 1). These nine types of treatment may be divided into two groups: With Nos. 1-6, a simple heating occurs; with Nos. 7-9, color producing chemicals are added during the process. Case No.6 may be regarded separately, since with this treatment, natural-looking fingerprint inclusions are generated in synthetic stones.
Heat treatment
This represents a normal annealing (but an extremely high temperature), a process which is well-known and applied to amethyst, zircon, topaz, tourmaline, etc. The new color is considered to be stable. Corundum treated after the processes Nos. 1-5 may be traded without complementary designation according to the regulations of CIBJO colored stones commission (CIBJO 1981).
For example, process No. 3 can be demonstrated with blue sapphire as follows: iron and titanium in the form of Fe/Ti-pairs in the corundum crystal lattice are responsible for the blue color in sapphires (Schmetzer & Bank, 1981). If one of the two partners is less abundant, its deficiency cannot be compensated by addition of the other partner. The solubility of iron and titanium is higher at high temperatures than at low temperatures. If a corundum saturated in Fe and Ti cools slowly, TiO2 is able to unmix from the corundum lattice as rutile (or silk). In this way, Ti is eliminated as a color producing component. On the other hand, by reductive heating a light blue rutile containing corundum to 1600°C and cooling it rapidly, one may obtain stones with intense blue color and a better transparency. The rutile has dissolved and joined with the possibly present iron to form the color yielding Fe/Ti pairs (Fe²+ / Ti4+ charge transfer).
Heat treatment processes used on sapphires and rubies (after K Nassau, 1981)
1. Treatment: Heating only
Specific process: Moderate temperature (1300°C)
Result: Develops potential asterism
2. Treatment: Heating only
Specific process: High temperature (1600°C) / rapid cooling
Result: Removes silk and asterism
3. Treatment: Heating only
Specific process: Reductive heating (1600°C)
Result: Develops potential blue color
4. Treatment: Heating only
Specific process: Oxidative heating (1600°C)
Result: Diminishes blue color
5. Treatment: Heating only
Specific process: Extended heating (1800°C)
Result: Diminishes Verneuil banding and strain
6. Treatment: Heating under unknown conditions (this process is used on synthetic material to generate inclusions with a natural appearance)
Specific process: ?
Result: Introduces fingerprint inclusions
7. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add TiO2
Result: Produces asterism
8. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add TiO2 and / or Fe2 O3
Result: Produces blue color
9. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add Cr2 O3, NiO, etc
Result: Produces other colors
Diffusion treatment
Method Nos. 7-9 are completely different from the above because minute quantities of ‘trace elements’ are added during the process. Proof of such a treatment is important for more than commercial reasons, since these products must be labeled ‘treated corundum’ according to the rules of CIBJO. The introduction of the ‘traces’ is diffusion induced. At the high temperature of 1700°C, the crystal lattice of corundum is somewhat expanded. The atoms are more mobile and interatomic distances enlarged relative to the cold state. Under conditions near the melting point, the iron or titanium present in higher concentrations outside the crystal is able to travel a short distance into the crystal. The depth of this diffusion process is dependant on the temperature and the duration of the treatment. Partial melting at the surface is frequently brought about by the strong heating, as well as by the reduction in melting point temperature caused by ‘trace elements’. The polished faces of a stone are dotted with tiny pits and droplets and must be repolished.
However, the diffusion treatment only reaches superficial areas. By replolishing a diffusion-treated corundum, its former colorlessness may be brought out again.
Occasionally, diffusion-treated corundums are incorrectly termed ‘coated sapphires’. In contrast to beryl with an overgrowth of synthetic emerald (after Lechleitner), diffusion-treated corundum does not display a ‘cultivated’ layer, but a barely measurable quantity of color has been soaked by the surface.
The diffusion method is not only used for producing blue corundum but is also employed with other elements to produce red (chromium), padparadscha and other colors.
Features of heat treated corundums
The raw material from which the following features are described are sapphires from Sri Lanka. They form the bulk of treatable material which reaches a high quality. Initially, these sapphires were weak in color, partially interspersed with silk, colored in narrow bands only, or of a yellowish cloudiness. With the sudden and intense heating which usually last one to two days, tension fractures may develop. Endangered regions are located at material inhomogenities. Therefore, tension cracks will most probably develop around inclusions and at the surface. The differential dilations of mineral, gas, and fluid inclusions contribute additionally to the formation of fissures. This mechanism occurs in nature during the metamorphism of rocks. But due to the rapid rates of artificial heating, these inclusions differ from those seen in natural stones. This is evident when comparing pictures of untreated corundums (Gubelin, 1973) with those presented in this paper.
In addition to the change of the original inclusions, we recognize the development of new forms of inclusions, for example, altered zonal structures of possibly former rutile; white spheric aggregates with a thorny surface. These ‘ping-pong balls’ frequently are surrounded by disc-shaped tension fissures. They resemble the natural, structured healing fissures in untreated Sri Lankan sapphires. Normally, the subtle healing fissures similar to insect wings transform to more bulky forms as hoses or rows of droplets; may show a type of tension crack for corundum, but similar to those seen in peridot. These fissures are again disc-shaped, iridescent and resemble atolls. Frequently, the center contains a tiny grain. The fissures are smooth and structured at the periphery only. A further feature of heat treated corundums is the grainy, pockmarked surface.
Normally, all facets or parts of the girdle are overlooked. The repolished girdle frequently is composed of several steps.
Features of diffusion treated corundums
A dark ring rimming the stone near the girdle is the first recognizable characteristic in diffusion treated stones. This sign is visible with the naked eye. In this zone, the stone is thin and the effect of the diffusion-layer is more prominent. In the center, we find in many cases a ‘hole’ of color. Here the effect of the diffusion layer is weakest. The girdle may appear colorless if the diffusion layer has been removed totally when repolished. Damaged spots and small pits in the surface of a pre-cut stone ready for treatment facilitate reinforced absorption of the coloring elements. A crack, i.e contact of two surfaces leads to a double diffusion layer, and therefore to a stronger color reception. Also concentrations of color in depressions are frequently encountered.
The recognition of corundum colored by a diffusion process should not present great difficulties. In most cases it will suffice to look at the stones in front of a diffusely bright background when they are immersed in a liquid with a high refractive index. At low magnification, the stronger colored facet edges are easily visible. Also, due to unequal forces applied during the repolishing, the differences in saturation of the individual facets are visible in immersion.
For the past two years blue sapphires with good color and pleasing size have become more abundant in the trade. Surprisingly, these stones are offered in lots in which the individual stones are uniformly colored. This is not common with larger gems of high value. Initially, we dealt with such sapphires very carefully and objectively due to a vague suspicion.
During the course of our investigation (Bosshart 1981) the subject of heat treatment of corundum has been brought up at various international meetings of gemologists. Finally, Nassau, Crowningshield and Liddicoat went public with some presentations, which if not quite complete are fairly comprehensive. This report is supplementary state of the author to a recent publication (Hanni 1982).
Heat treatment of corundum has long been practiced, on the one hand after indigenous methods in the countries of origin (i.e. Sri Lanka), on the other hand after an industrial method employed since 1973. With local methods, controlling of temperature and environment is not satisfactorily possible. Because of this, the results are unreliable. Application of the industrial method, carried out in the USA and Thailand, guarantees constant, controlled conditions and leads to the desired results. Let us consider the patents of Union Carbide in 1973 as a starting point. In these patents, techniques are described which allow (at first applied to synthetics only) a homogenization or improvement of the color or the development of asterism. Over the last years, these processes have been tried and improved on natural corundum. Presently, masters of such techniques reside in Thailand. Their latest surprising creations are yellow to orange corundums produced by heat treating raw material corundum of an as yet undescribed type.
The aim of heat treatment is to reach a uniform distribution of color, to clarify or to increase the color, or to attain better purity by dissolving certain inclusions. Critical is whether these stones have absorbed foreign matter during the process of heat treatment, or the required improvement was achieved with those components already present in the stone. Recently, Dr Nassau has reviewed the different processes (Nassau 1981, tab 1). These nine types of treatment may be divided into two groups: With Nos. 1-6, a simple heating occurs; with Nos. 7-9, color producing chemicals are added during the process. Case No.6 may be regarded separately, since with this treatment, natural-looking fingerprint inclusions are generated in synthetic stones.
Heat treatment
This represents a normal annealing (but an extremely high temperature), a process which is well-known and applied to amethyst, zircon, topaz, tourmaline, etc. The new color is considered to be stable. Corundum treated after the processes Nos. 1-5 may be traded without complementary designation according to the regulations of CIBJO colored stones commission (CIBJO 1981).
For example, process No. 3 can be demonstrated with blue sapphire as follows: iron and titanium in the form of Fe/Ti-pairs in the corundum crystal lattice are responsible for the blue color in sapphires (Schmetzer & Bank, 1981). If one of the two partners is less abundant, its deficiency cannot be compensated by addition of the other partner. The solubility of iron and titanium is higher at high temperatures than at low temperatures. If a corundum saturated in Fe and Ti cools slowly, TiO2 is able to unmix from the corundum lattice as rutile (or silk). In this way, Ti is eliminated as a color producing component. On the other hand, by reductive heating a light blue rutile containing corundum to 1600°C and cooling it rapidly, one may obtain stones with intense blue color and a better transparency. The rutile has dissolved and joined with the possibly present iron to form the color yielding Fe/Ti pairs (Fe²+ / Ti4+ charge transfer).
Heat treatment processes used on sapphires and rubies (after K Nassau, 1981)
1. Treatment: Heating only
Specific process: Moderate temperature (1300°C)
Result: Develops potential asterism
2. Treatment: Heating only
Specific process: High temperature (1600°C) / rapid cooling
Result: Removes silk and asterism
3. Treatment: Heating only
Specific process: Reductive heating (1600°C)
Result: Develops potential blue color
4. Treatment: Heating only
Specific process: Oxidative heating (1600°C)
Result: Diminishes blue color
5. Treatment: Heating only
Specific process: Extended heating (1800°C)
Result: Diminishes Verneuil banding and strain
6. Treatment: Heating under unknown conditions (this process is used on synthetic material to generate inclusions with a natural appearance)
Specific process: ?
Result: Introduces fingerprint inclusions
7. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add TiO2
Result: Produces asterism
8. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add TiO2 and / or Fe2 O3
Result: Produces blue color
9. Treatment: Diffusion of impurities into the material (extended heating at 1800°C)
Specific process: Add Cr2 O3, NiO, etc
Result: Produces other colors
Diffusion treatment
Method Nos. 7-9 are completely different from the above because minute quantities of ‘trace elements’ are added during the process. Proof of such a treatment is important for more than commercial reasons, since these products must be labeled ‘treated corundum’ according to the rules of CIBJO. The introduction of the ‘traces’ is diffusion induced. At the high temperature of 1700°C, the crystal lattice of corundum is somewhat expanded. The atoms are more mobile and interatomic distances enlarged relative to the cold state. Under conditions near the melting point, the iron or titanium present in higher concentrations outside the crystal is able to travel a short distance into the crystal. The depth of this diffusion process is dependant on the temperature and the duration of the treatment. Partial melting at the surface is frequently brought about by the strong heating, as well as by the reduction in melting point temperature caused by ‘trace elements’. The polished faces of a stone are dotted with tiny pits and droplets and must be repolished.
However, the diffusion treatment only reaches superficial areas. By replolishing a diffusion-treated corundum, its former colorlessness may be brought out again.
Occasionally, diffusion-treated corundums are incorrectly termed ‘coated sapphires’. In contrast to beryl with an overgrowth of synthetic emerald (after Lechleitner), diffusion-treated corundum does not display a ‘cultivated’ layer, but a barely measurable quantity of color has been soaked by the surface.
The diffusion method is not only used for producing blue corundum but is also employed with other elements to produce red (chromium), padparadscha and other colors.
Features of heat treated corundums
The raw material from which the following features are described are sapphires from Sri Lanka. They form the bulk of treatable material which reaches a high quality. Initially, these sapphires were weak in color, partially interspersed with silk, colored in narrow bands only, or of a yellowish cloudiness. With the sudden and intense heating which usually last one to two days, tension fractures may develop. Endangered regions are located at material inhomogenities. Therefore, tension cracks will most probably develop around inclusions and at the surface. The differential dilations of mineral, gas, and fluid inclusions contribute additionally to the formation of fissures. This mechanism occurs in nature during the metamorphism of rocks. But due to the rapid rates of artificial heating, these inclusions differ from those seen in natural stones. This is evident when comparing pictures of untreated corundums (Gubelin, 1973) with those presented in this paper.
In addition to the change of the original inclusions, we recognize the development of new forms of inclusions, for example, altered zonal structures of possibly former rutile; white spheric aggregates with a thorny surface. These ‘ping-pong balls’ frequently are surrounded by disc-shaped tension fissures. They resemble the natural, structured healing fissures in untreated Sri Lankan sapphires. Normally, the subtle healing fissures similar to insect wings transform to more bulky forms as hoses or rows of droplets; may show a type of tension crack for corundum, but similar to those seen in peridot. These fissures are again disc-shaped, iridescent and resemble atolls. Frequently, the center contains a tiny grain. The fissures are smooth and structured at the periphery only. A further feature of heat treated corundums is the grainy, pockmarked surface.
Normally, all facets or parts of the girdle are overlooked. The repolished girdle frequently is composed of several steps.
Features of diffusion treated corundums
A dark ring rimming the stone near the girdle is the first recognizable characteristic in diffusion treated stones. This sign is visible with the naked eye. In this zone, the stone is thin and the effect of the diffusion-layer is more prominent. In the center, we find in many cases a ‘hole’ of color. Here the effect of the diffusion layer is weakest. The girdle may appear colorless if the diffusion layer has been removed totally when repolished. Damaged spots and small pits in the surface of a pre-cut stone ready for treatment facilitate reinforced absorption of the coloring elements. A crack, i.e contact of two surfaces leads to a double diffusion layer, and therefore to a stronger color reception. Also concentrations of color in depressions are frequently encountered.
The recognition of corundum colored by a diffusion process should not present great difficulties. In most cases it will suffice to look at the stones in front of a diffusely bright background when they are immersed in a liquid with a high refractive index. At low magnification, the stronger colored facet edges are easily visible. Also, due to unequal forces applied during the repolishing, the differences in saturation of the individual facets are visible in immersion.
Subscribe to:
Posts (Atom)