(via Wahroongai News, Volume 32, Number 7, July 1998)
Table of absorption lines for gems and minerals: This section deals with the absorption spectra of gemstones by using the spectroscope. The units are measured in Angstrom units (A), (One Angstrom = one ten millioneth of a millimeter), all figures are in Angstrom units. The gem spectroscope is used on transparent materials but thin slices of opaque materials can be used as long as light passes through it. Strong absorption lines are bracketed and weak lines have no brackets.
Color bands for the spectroscope
Red: 7800 – 6400
Orange: 6400 – 5950
Yellow: 5950 – 5700
Green: 5700 – 5000
Blue: 5000 – 4500
Purple: 4500 – 3800
Agate, dyed yellow: (7000), 6650, 6350
Actinolite: 5030, 4315
Alexandrite, green direction: (6805), 6785, 6650, (6550), 6490, 6450, (6400), (5550)
Alexandrite, red direction: 6805, (6785), 6550, 6450, 6050, 5400, (4720)
Almandine: 6170, (5760), (5270), (5050), 4620, 4380, 4280, 4040, 3930
Amethyst: 5500, 5200
Andalusite: 5535, (5505), 5475, 5250, 5180, 5060, 4950, (4550), 4475, (4360)
Apatite, yellow green: 6053, 6025, 5975, (5855), (5772), 5335, 5295, 5270
Aventurine: 6820, 6490
Axinite: 5320, (5120), (4920), (4660), 4400, 4150
Azurite: 5000
Beryl, dyed blue: 7050, 6850, 6450, 6250, 6050, 5870
Calcite: (5820)
Chalcedony, dyed blue: 6900, 6600, 6270
Chalcedony, dyed green: 7050, 6700, 6450
Chrysoberyl: 5040, 4950, 4850, (4450)
Chrysoprase, dyed: 6320, 4439
Chrysoprase: 4439
Danburite: 5900, 5860, (5845), 5840, 5830, 5820, 5805, 5780, 5760, 5730, 5710
Demantoid: (7100), 6930, (6400), (6220), 4850, 4640, 4430
Diamond, colorless to yellow: (4780), 4650, 4510, 4350, 4230, (4155), 4015, 3900
Diamond, brown to green: 537-, (5040), 4980
Diamond, yellow to brown: 5760, 5690, 5640, 5580, 5500, 5480, 5230, 4935, 4800, 4600
Diamond, artificial color yellow: (5940), 5040, (4980), 4780, 4650, 4510, 4350, 4230, 4155
Diamond, artificial color green: (7410), (5040), (4980), 4650, 4510, 4350, 4230, 4155
Diamond, artificial color brown: (7410), 5940, (5040), (4980), 4780, 4650, 4510, 4350, 4230, 4155
Diopside: (5470), 5080, (5050), (4930), 4560
Chrome diopside: 6700, 6550, 6350, 5080, 5050, 4900
Dioptase: 5700, 5600, 4650-4000
Ekanite: 6651, 6375
Emerald: (6835), (6806), 6620, 6460, (6370), 6060, 5940, (6300-5800)
Emerald, synthetic: 6830, 6805, 6620, 6460, (6375), 6300-5800, 6060, 5940, 4774
Enstatite: (5475), 5090, (5058), 5025, 4830, 4720, 4590, 4490, 4250
Chrome Enstatite: 6880, 6690, 5060
Epidote: 4750, (4550), 4350
Euclase: (7065), (7040), 6950, 6880, 6600, (6500), (6390), 4680, 4550
Fluorite, green: 6400, 6006, (5850), 5700, 5530, 5500, 4520, 4350
Fluorite, yellow: 5450, 5150, 4900, 4700, 4520
Gahnite: (6320), 5920, 5770, 5520, 5080, (4800), (4590), 4430, 4330
Grossular: 6300
Hematite: 7000, 6400, 5950, 5700, 4800, 4500, 4250, 4000
Hessonite: 5470, 4900, 4545, (4350)
Hiddenite: (6905), (6860), 6690, 6460, (6200), (4375), 4330
Hypersthene: 5510, (5475), (5058), 4820, 4485
Idocrase, green: 5300, 4870, (4610)
Iolite: 6450, 5930, 5850, 5350, (4920), (4560), 4360, 4260
Jadeite, green: (6915), 6550, 6300, 4950, 4500, (4375), 4330
Jadeite, artificial green: 6650, 6550, 6450
Kornerupine: 5400, (5080), 4630, (4460), 4300
Kyanite: 7060, 6890, 6710, (4460), 4330
Nephrite: 6890, (5090), 4900, 4600
Obsidian: 6800, 6700, 6600, 6500, 6350, 5950, 5550, 5000
Opal, fire: 7000-6400, 5900-4000
Orthoclase: 4480, 4200
Peridot: 6530, 5530, 5290, (4970), (4950), (4930), (4730), 4530
Petalite: 4540
Pyrope: (6870), (6850), 6710, 6500, (6200-5200), 5050
Quartz, synthetic blue: 6450. 5850, 5400, 5000-4900
Rhodochrosite: 5510, 4545, 4100, 3910, 3830, 3780, 3630
Rhodonite: 5480, 5030, 4550, 4120, 4080
Ruby: (6942), (6928), 6680, 6592, 6100-5000, (4750), (4685)
Sapphire, blue: (4710), (4600), 4550, (4500), 3790
Sapphire, yellow: (4710), (4600), (4500)
Sapphire, green: 4710, 4600-4500
Scheelite: (5840)
Serpentine: 4970, 4640
Sillimanite: 4620, 4410, 4100
Sinhalite: 5260, 4925, 4760, (4630), 4520, 4355
Scapolite, pink: 6630, 6520
Spessartite: 4950, (4845), 4810, 4750, (4620), 4570, 4550, 4400, 4350, 4320, 4240, 4120, 4060, 3940
Sphalerite: 6900, 6650, (6510)
Sphene: 5900, (5860), (5820), 5800, 5750, 5340, 5300, 5280
Spinel, red: (6855), 6840, (6750), (6650), 6560, 6500, 6420, 6320, (5950-4900), 4550
Spinel, blue: (6350), (5850), (5550), 5080, (4780), (4580), 4430, 4330
Spinel, synthetic blue: 6340, 5800, 5440, 4850, 4490
Spinel, synthetic green: 6200, 5800, 5700, 5500, 5400
Taaffeite: 5580, 5530, 4780
Tanzanite: 7100, 6910, (5950), 5280, 4550
Topaz, pink: (6828)
Tremolite: (6840), 6500, 6280
Turquoise: 4600, 4320, 4220
Tourmaline, red: 5550, 5370, 5250-4610, (4560), (4510), 4280
Tourmaline, green: (4970), (4610), 4150
Variscite: 6880, 6500
Willemite: 5830, 5400, 4900, 4425, 4315, (4210)
Zircon, normal: 6910, 6890, 6625, 6605, (6535), 6210, 6150, 5895, 5620, 5375, 5160, 4840, 4600, 4320
Zircon, low: (6530), 5200
Monday, March 19, 2007
What Is An Antique
(via Wahroongai News, Volume 32, Number 5, May 1998)
The following definition of an antique was discovered in the first newsletter of 1998 from the Queensland Antique Collector’s Society Inc.
Definition of Antiques
One of the strengths of the Society is the very wide range of subjects that can be covered under the definition of antiques, e.g. porcelain, silver, furniture, art. What is clear is that definition (of what is an antique) has suffered changes.
Until quite recently, the accepted opinion in England was that antique applied to articles made before about 1830, i.e. not including Victorian items. In view of the factors of supply and demand, English dealers have accepted the international convention that antique means more than 100 years old. This includes basically all Victorian pieces, but excludes Edwardian and most Art Nouveau.
American dealers have taken the view that antique refers to pieces made more than 30 years ago, and so would include original material of the Beatles and Elvis Presley. While this concept may appear startling to traditional conventions, the definition can change depending on personal perspective.
In other cultures, goods may be described as a little bit old referring to wares that were in use by grandparents. There are collectors who seek items because their grandma had one of those. The differing age of collectors, from 20 to 70 plus means that the time-frame for defining the previous two generations becomes flexible.
Most antique dealers take pragmatic view that antique refers to articles no longer made, for which there is demand. If pushed, they may limit the scope of the definition to items made before the Second World War, thus including Art Deco.
The following definition of an antique was discovered in the first newsletter of 1998 from the Queensland Antique Collector’s Society Inc.
Definition of Antiques
One of the strengths of the Society is the very wide range of subjects that can be covered under the definition of antiques, e.g. porcelain, silver, furniture, art. What is clear is that definition (of what is an antique) has suffered changes.
Until quite recently, the accepted opinion in England was that antique applied to articles made before about 1830, i.e. not including Victorian items. In view of the factors of supply and demand, English dealers have accepted the international convention that antique means more than 100 years old. This includes basically all Victorian pieces, but excludes Edwardian and most Art Nouveau.
American dealers have taken the view that antique refers to pieces made more than 30 years ago, and so would include original material of the Beatles and Elvis Presley. While this concept may appear startling to traditional conventions, the definition can change depending on personal perspective.
In other cultures, goods may be described as a little bit old referring to wares that were in use by grandparents. There are collectors who seek items because their grandma had one of those. The differing age of collectors, from 20 to 70 plus means that the time-frame for defining the previous two generations becomes flexible.
Most antique dealers take pragmatic view that antique refers to articles no longer made, for which there is demand. If pushed, they may limit the scope of the definition to items made before the Second World War, thus including Art Deco.
Bewitching Jewelry
By Carl H Giles & Barbara Ann Williams
A.S.Barnes and Co, Inc
1976 ISBN 0-498-01654-4
A S Barnes and Co writes:
Bewitching Jewelry opens the occult showcase of amulets and talismans. It examines the glittering and mystic trappings of the supernatural. Lean what the well-dressed witches are wearing—and why! Rip away the ritual robe and peek at the pendants, bracelets, rings, and necklaces of witchcraft.
Amulets and talismans are among the most powerful of all psychic baubles. Mysticism is universal, and amulets are common to all people. Talismans act more as lures to make things happen; amulets are usually used as shields, to safeguard the wearer from misfortunes.
Psychics claim that an amulet possesses supernatural powers, while a talisman may be a piece of jewelry or any object that has been endowed with special powers through occult ceremonies. Almost any object may become a talisman. Choosing the right amulet and talismans for your black arts jewelry box may help you become happier, healthier, and wealthier.
This witch’s jewel case exhibits the ornamental wonders that may help you achieve goals and fulfill ambitions. Learn how to recognize the pieces of bewitching jewelry that many men and women are wearing. You will know what people are trying to accomplish just by observing their occult jewelry.
Is your closest friend trying to revitalize her mate by wearing that special medallion? Should you wear a certain item to stop gossip? Will the piece of jewelry and the right ritual words really get rid of a headache? Is it possible for some occult jewelry to increase your confidence? Amulets and talismans may do all these things.
Some occult stones and metals may be used for solving romantic problems. Regardless of what one wants to obtain or accomplish, there seems to be some jewelry appropriate to the situation. Would you wear a voodoo doll for love or hate? You can take one for whatever scheme you need after reading the chapter on how to choose talismans.
Should you wear a witch’s belt? You may make one with the directions outlines in this volume. Find out how you can fashion some special creations. Inventory your wishes and wants, and select psychic designs that will complement your wardrobe.
Bewitching Jewelry may improve your life by giving you a detailed look at all the occult ornaments needed for an occult jewelry box. The supernatural charms and jewelry will radiate a great, new betwitching you on the outside and may generate a beautiful new mental you on the inside. Start doing your betwitching best.
A.S.Barnes and Co, Inc
1976 ISBN 0-498-01654-4
A S Barnes and Co writes:
Bewitching Jewelry opens the occult showcase of amulets and talismans. It examines the glittering and mystic trappings of the supernatural. Lean what the well-dressed witches are wearing—and why! Rip away the ritual robe and peek at the pendants, bracelets, rings, and necklaces of witchcraft.
Amulets and talismans are among the most powerful of all psychic baubles. Mysticism is universal, and amulets are common to all people. Talismans act more as lures to make things happen; amulets are usually used as shields, to safeguard the wearer from misfortunes.
Psychics claim that an amulet possesses supernatural powers, while a talisman may be a piece of jewelry or any object that has been endowed with special powers through occult ceremonies. Almost any object may become a talisman. Choosing the right amulet and talismans for your black arts jewelry box may help you become happier, healthier, and wealthier.
This witch’s jewel case exhibits the ornamental wonders that may help you achieve goals and fulfill ambitions. Learn how to recognize the pieces of bewitching jewelry that many men and women are wearing. You will know what people are trying to accomplish just by observing their occult jewelry.
Is your closest friend trying to revitalize her mate by wearing that special medallion? Should you wear a certain item to stop gossip? Will the piece of jewelry and the right ritual words really get rid of a headache? Is it possible for some occult jewelry to increase your confidence? Amulets and talismans may do all these things.
Some occult stones and metals may be used for solving romantic problems. Regardless of what one wants to obtain or accomplish, there seems to be some jewelry appropriate to the situation. Would you wear a voodoo doll for love or hate? You can take one for whatever scheme you need after reading the chapter on how to choose talismans.
Should you wear a witch’s belt? You may make one with the directions outlines in this volume. Find out how you can fashion some special creations. Inventory your wishes and wants, and select psychic designs that will complement your wardrobe.
Bewitching Jewelry may improve your life by giving you a detailed look at all the occult ornaments needed for an occult jewelry box. The supernatural charms and jewelry will radiate a great, new betwitching you on the outside and may generate a beautiful new mental you on the inside. Start doing your betwitching best.
Sunday, March 18, 2007
If We Learn To Appreciate What Mines Produce, There Will Be Enough Rough
(via ICA Gazette, April 1990) E Julius Petsch writes:
“We have no rough stones available.”
“There is no more rough.”
“This is the last lot from this mine.”
How many times have I heard these arguments? And in almost every case the people using them were wrong.
There have always been rough gemstones available. I can look back on thirty years of experience in the rough colored gemstone business and during each buying trip those years I found that were more rough stones available than money to pay for them.
During these years I have also collected a great deal of experience in mining and it is very rare to hear about a mine that is actually depleted. What most often disturbs the steady flow of rough is the lack of long term planning and lack of capital to finance proper mining. In fact, even today, only a very few mines are being exploited with the expertise and knowledge of experienced mining engineers and geologists. Many mining enterprises are also handicapped by lengthy quarrels about mining rights or legal possession of the claims. Mines are invaded by prospectors who only dig holes in the ground instead of carrying out a proper mining plan. There are also unrealistic or exaggerated price demands from inexperienced mine owners or prospectors which discourage buyers from trying to create a market for a product.
It also must not be forgotten that in some gemstone producing countries the existence of very rigid laws concerning the export of rough constrains the market. In other producing countries, the uncertain political situation impedes the production of rough gemstones or the government interferes with free trade and mining, often imposing unsupportable conditions on those who would be willing to work in this industry.
Most of the mines and mining areas which are producing today are not recent discoveries. Many mines have been producing for decades without interruption, some even for a century. The number of genuinely new discoveries of gemstone deposits is very small.
If research and prospecting for gemstone deposits were carried out more systematically, we would find that there are still vast reserves available. Most of the mining areas I know are rich with gemstone deposits. The Carnaiba emerald mine in Brazil, for example, has been proven to extend for 12 kilometers. The tourmaline bearing pegmatite of the Cruzeiro area, also in Brazil, in the State of Minas Gerais, measures many square kilometers in area. This deposit has been exploited steadily for more than fifty years. I could give very many more examples of the richness of existing deposits, not only in Brazil, but also in Australia, Africa, and the United States.
No gemstone mine produces only the best and finest qualities. The majority of the production is always the lower qualities. But this does not mean that this material is not beautiful or useful to the jewelry industry: this is a matter of taste and fashion. Cabochons, beads and tumbled stones are very often cut from the lower qualities. Although they are not clean and show inclusions instead of being transparent, they are often of beautiful color and show interesting layers, veins, and patterns. These stones are not as valued primarily because they are found in large quantities. Very often, jewelry set with a cabochon cut stone can be as fashionable, attractive, and impressive as jewelry set with its faceted counterpart.
If we could adjust the demand from the designers and manufacturers of jewelry to fit the availability of the various qualities of rough gemstones, we would always have sufficient material at our disposal to cover the demand for cut gemstones. Demand determines the price for each quality.
If however, we insist on only selling clean gemstones with intense pure colors, the availability of suitable rough is artificially decreased. I am convinced that the concentration of demand in narrow range of material has been created unnecessarily. The consumer always appreciates the natural beauty of a gemstone, be it transparent or translucent, faceted or cabochon cut, bead or tumbled. It is the gemstone itself with its natural beauty that the buyer loves, even more when that beauty is complemented by a fine gold or silver setting.
I am sure that colored gemstone rough—and therefore cut colored gemstones—will always be available, provided we can finally accept the wide range of qualities naturally produced by the world’s gemstone mines.
“We have no rough stones available.”
“There is no more rough.”
“This is the last lot from this mine.”
How many times have I heard these arguments? And in almost every case the people using them were wrong.
There have always been rough gemstones available. I can look back on thirty years of experience in the rough colored gemstone business and during each buying trip those years I found that were more rough stones available than money to pay for them.
During these years I have also collected a great deal of experience in mining and it is very rare to hear about a mine that is actually depleted. What most often disturbs the steady flow of rough is the lack of long term planning and lack of capital to finance proper mining. In fact, even today, only a very few mines are being exploited with the expertise and knowledge of experienced mining engineers and geologists. Many mining enterprises are also handicapped by lengthy quarrels about mining rights or legal possession of the claims. Mines are invaded by prospectors who only dig holes in the ground instead of carrying out a proper mining plan. There are also unrealistic or exaggerated price demands from inexperienced mine owners or prospectors which discourage buyers from trying to create a market for a product.
It also must not be forgotten that in some gemstone producing countries the existence of very rigid laws concerning the export of rough constrains the market. In other producing countries, the uncertain political situation impedes the production of rough gemstones or the government interferes with free trade and mining, often imposing unsupportable conditions on those who would be willing to work in this industry.
Most of the mines and mining areas which are producing today are not recent discoveries. Many mines have been producing for decades without interruption, some even for a century. The number of genuinely new discoveries of gemstone deposits is very small.
If research and prospecting for gemstone deposits were carried out more systematically, we would find that there are still vast reserves available. Most of the mining areas I know are rich with gemstone deposits. The Carnaiba emerald mine in Brazil, for example, has been proven to extend for 12 kilometers. The tourmaline bearing pegmatite of the Cruzeiro area, also in Brazil, in the State of Minas Gerais, measures many square kilometers in area. This deposit has been exploited steadily for more than fifty years. I could give very many more examples of the richness of existing deposits, not only in Brazil, but also in Australia, Africa, and the United States.
No gemstone mine produces only the best and finest qualities. The majority of the production is always the lower qualities. But this does not mean that this material is not beautiful or useful to the jewelry industry: this is a matter of taste and fashion. Cabochons, beads and tumbled stones are very often cut from the lower qualities. Although they are not clean and show inclusions instead of being transparent, they are often of beautiful color and show interesting layers, veins, and patterns. These stones are not as valued primarily because they are found in large quantities. Very often, jewelry set with a cabochon cut stone can be as fashionable, attractive, and impressive as jewelry set with its faceted counterpart.
If we could adjust the demand from the designers and manufacturers of jewelry to fit the availability of the various qualities of rough gemstones, we would always have sufficient material at our disposal to cover the demand for cut gemstones. Demand determines the price for each quality.
If however, we insist on only selling clean gemstones with intense pure colors, the availability of suitable rough is artificially decreased. I am convinced that the concentration of demand in narrow range of material has been created unnecessarily. The consumer always appreciates the natural beauty of a gemstone, be it transparent or translucent, faceted or cabochon cut, bead or tumbled. It is the gemstone itself with its natural beauty that the buyer loves, even more when that beauty is complemented by a fine gold or silver setting.
I am sure that colored gemstone rough—and therefore cut colored gemstones—will always be available, provided we can finally accept the wide range of qualities naturally produced by the world’s gemstone mines.
Magnolia
Memorable quote (s) from the movie:
Jim Kurring (John C Reilly): Let me tell you something, this is not an easy job. I get a call on the radio, dispatch, it's bad news. And it stinks. But this is my job and I love it. Because I want to do well - in this life and in this world, I want to do well. And I want to help people. And I might get twenty bad calls a day. But one time I can help someone and make a save - correct a wrong or right a situation - then I'm a happy cop. And as we move through this life we should try and do good. Do good... And if we can do that, and not hurt anyone else, well... then...
Jim Kurring (John C Reilly): Let me tell you something, this is not an easy job. I get a call on the radio, dispatch, it's bad news. And it stinks. But this is my job and I love it. Because I want to do well - in this life and in this world, I want to do well. And I want to help people. And I might get twenty bad calls a day. But one time I can help someone and make a save - correct a wrong or right a situation - then I'm a happy cop. And as we move through this life we should try and do good. Do good... And if we can do that, and not hurt anyone else, well... then...
Five Different Types Of Synthetic Diamond
(via The Canadian Gemmologist, Volume XIV, Number 1, Spring, 1993) Kurt Nassau writes:
Essentially all the apprehension felt in the diamond trade about the threat of synthetic diamonds is unjustified. It is largely the result of confusion about five groups of synthetic diamond that have quite different growth characteristics. Even scientists themselves often make statements which may be true of one of the five groups of synthetic diamond, but seem to apply to all synthetic diamonds.
As one example, it is true that yellow synthetic diamond can be grown in large, good quality crystals at a relatively low cost by the high pressure technique. Yet this statement does not generally apply to colorless or blue synthetic diamond made by the same process.
As another example, it is true that polycrystalline diamond films can be grown by the low pressure techniques to be a millimeter or more in thickness. Yet it is important to realize that these films are usually neither colorless nor transparent by diamond grading standards when approaching a millimeter in thickness. In addition, millimeter thickness is not achievable at present for single crystal synthetic diamond films even when grown on an existing diamond.
And lastly, there are a whole series of synthetic ‘diamond-like films’ which are too frequently labeled ‘synthetic diamond’, a totally incorrect and misleading usage. These films are usually neither clear nor transparent when of significant thickness. Moreover, they are definitely not diamond, any more than graphite or charcoal could properly be designated ‘diamond’ even though all are forms of carbon.
Confusion also arises from three additional points, which may need clarification. When a crystal grower claims that his crystals have ‘excellent’ quality or are ‘flawless’, he does not mean that they are flawless by gemological standard; usually it means that he can see through the layers or perhaps even read print with the crystal set on the paper, which may not be difficult when the layer is only a fraction of a millimeter in thickness.
The second point involves the definition of ‘diamond’ which is strictly defined as the cubic form of carbon. There is also a hard hexagonal form of carbon, properly designated lonsdaleite ‘hexagonal diamond’ which is erroneous because it means ‘hexagonal cubic caron’. So in the diamond thin-film business ‘diamond’ may not always mean diamond, but may also mean lonsdaleite or amorphous carbon.
Finally, a statement such as ‘a growth rate of one inch per week has been achieved’ does not mean that one inch has been grown; it may mean only that one thousandth of one inch was grown in one-thousandth of a week, that is in ten minutes. But growth rates do not always scale up.
The best way to understand the present rather confusing situation is to consider briefly the high-and low-pressure techniques and the five groups of synthetic diamond products.
Synthetic High Pressure Diamond
The high pressure technique for growth of synthetic diamond was discovered by H Tracy Hall at General Electric in 1955, using temperatures about 2000°C (3623°F) and pressure over one million pounds per square inch. At first, only grit could be made; GE announced gem size crystals in 1970.
Group 1: Synthetic High Pressure Yellow Diamond
Yellow synthetic diamond, colored by traces of nitrogen absorbed from the air during the growth, is readily grown by using a variety of metal solvents; crystals over 12mm across and over 14 carats in weight have been reported. By growing several layers with several small crystals per layer at one time, synthetic diamond slices used as heat sinks for transistors and integrated circuits can be produced economically. Several companies have the capability of doing this, including De Beers, GE and Sumitomo. The gemological properties of such synthetic high pressure yellow diamond have been described for example by Shigley et.al (1987). Identification should present no serious problems.
Group II: Synthetic High Pressure Colorless and Blue Diamond
For the colorless product, nitrogen must be excluded, and boron is additionally used to obtain a blue color. In both instances, special conditions must be used, such as aluminum in the solvent to remove nitrogen. This makes it more difficult to grow many crystals at one time. The characteristics of the products have been discussed by Koivula and Fryer (1984), and Shigley et.al (19860, and identification would probably present no serious problems if and when routine production, and therefore, a standardized product should happen.
Colorless and blue synthetic diamonds suitable for faceting have, indeed, been grown only on an experimental basis so far, and one can estimate that cost of production is not very different from that of natural diamond. To put this statement into perspective, synthetic colored gemstones, such as flux grown emerald, ruby, and so on, appear to be viable at a cost of less than one-tenth that of the equivalent quality natural material, but experience has shown that the market is very restricted except at even lower prices.
Thin Film Carbon Deposition
Various low pressure techniques using carbon-containing gases such as methane or acetylene and temperatures of 1200°C (2192°F) or below are used to grow a variety of types of diamond and other carbon-containing films under non-equilibrium conditions. Even acetylene torches have been used. For reviews of thin film work, see DeVries (1987), Angus and Hayman (1988), and Bachman and Messier (1989).
Group III: Synthetic Polycrystalline Diamond Films
When conditions are carefully controlled, polycrystalline diamond film s can be grown quite rapidly to become a millimeter or more in thickness. When very thin, these would not be readily detected, even by a thermal probe, and would probably not serve any useful purpose in gemology. Weight gain would be negligible and the surface hardness would not be changed significantly.
This last statement may be surprising, but a scratch test applied to a very thin diamond film covering a soft material would merely result in distortion of the substrate, and tearing and detaching of the film. If the film is thick, so that it could give a diamond reaction on a thermal probe ad provide a hard surface for a soft material, it would be visible during a gemological investigation. Moreover, adhesion of such polycrystalline diamond film is extremely poor to substances other than silicon, silcon carbide (moissanite), or diamond itself.
Group IV: Synthetic Single Crystal Diamond Films
This type of film appears to be great concern to some, because it seems to provide the threat of increasing the size of a natural diamond. Single crystal diamond films can indeed be grown on diamond surface by suitable adjustments of the low pressure techniques. Yet, a curious phenomenon occurs: the film only seems to reach a certain thickness, depending on the techniques used. If one tries to force it to continue to grow, then it either stops, turn polycrystalline (when the remarks under Group III apply), or something else happens.
Such films often contain stacking faults and may then be not diamond but lonsdaleite. It is of course possible that someone may discover someday how to keep the films growing, but work on this topic has been underway for over 30 years; a solution just does not seem easy to find. Adhesion is a problem on materials other than those listed above.
One interesting possibility is that a very thin synthetic crystal blue diamond film coating could enhance the appearance of yellow cape-series diamonds. This has been done experimentally (see Fritisch, 1991). Such a film should be as easily detected as a thin blue lacquer layer, by standard gemological testing: the concentration of color in the surface layer can be seen by immersion even in water. The acceptability of such an overgrowth would depend on the nomenclature; it might well be decided that this must be called a ‘natural-synthetic composite diamond.’
Group V: Diamond-like Films
A wide variety of different films which are not diamond but are often so labelled can be deposited quite rapidly and to millimeter thickness by various modifications of the low pressure technique. Some of these are non-crystalline amorphous or glassy films. Some contain significant amounts of hydrogen, up to one hydrogen per carbon, and should then be called hydrocarbon films. Some are partly crystalline but, instead of containing only sp-3 bonding as does diamond, also contain some sp-2 bondings as does graphite. Some have stacking sequences leading to hexagonal lonsdaleite. The materials considered in this group do not have the cube symmetry of diamond.
Additional names that have been used include amorphous carbon, amorphous hydrocarbon, dense (hydro) carbon, hard or superhard carbon, and non-diamond carbon films. All of these names may be appropriate for some such films, but the name ‘diamond’ is definitely incorrect. The hardness may vary from less than 8 to over 9, the color may be black, grey, or near colorless (particularly if very thin), and adhesion is a problem on most materials. It is difficult to visualize any application of such films in the gem field.
The Lessons From Other Synthetics
It is worth examining briefly what happens when usable synthetic gemstones first arrived in the trade. The result was the same each time, whether the product was synthetic ruby in 1905, synthetic sapphire in 1910, synthetic star corundum in 1947, synthetic emerald in 1950, synthetic alexandrite in 1972, and so on. At first there was considerable apprehension, both with respect to the effect on the trade, and also with respect to the ability to distinguish the new synthetic from natural. Each time, this stage was followed by the realization that synthetic could be distinguished from the natural with little trouble, and that synthetic filled a different niche from the natural.
In each instance there was essentially no long term effect on the market for the natural material. It is perhaps worth repeating that synthetics have only been successful in their own niches at a price less than one tenth that of the natural material. Overgrowth of a synthetic over the surface of a natural gemstone has been possible since about 1960, when Lechleitner grew a thin layer of very dark green synthetic emerald over pale natural beryl performs. This has not been a successful product in the market place to date.
In conclusion, there is no significant impact to be expected from synthetic diamond, whether produced in bulk form by the high pressure technique or in the thin film form by the low pressure technique. As always, a steady improvement of growth technology must certainly be anticipated. Significant future breakthroughs are always a possibility and would then change the present status. But they should be of concern only when they happen.
For example, there is little likelihood of D flawless synthetic diamond in carat and larger sizes and at a production cost to make it viable as a synthetic as discussed above for many years to come. After all, someone might just discover next week a new diamond mine containing huge quantities of large flawless stones; while such a discovery is not impossible, it is merely highly improbable.
Essentially all the apprehension felt in the diamond trade about the threat of synthetic diamonds is unjustified. It is largely the result of confusion about five groups of synthetic diamond that have quite different growth characteristics. Even scientists themselves often make statements which may be true of one of the five groups of synthetic diamond, but seem to apply to all synthetic diamonds.
As one example, it is true that yellow synthetic diamond can be grown in large, good quality crystals at a relatively low cost by the high pressure technique. Yet this statement does not generally apply to colorless or blue synthetic diamond made by the same process.
As another example, it is true that polycrystalline diamond films can be grown by the low pressure techniques to be a millimeter or more in thickness. Yet it is important to realize that these films are usually neither colorless nor transparent by diamond grading standards when approaching a millimeter in thickness. In addition, millimeter thickness is not achievable at present for single crystal synthetic diamond films even when grown on an existing diamond.
And lastly, there are a whole series of synthetic ‘diamond-like films’ which are too frequently labeled ‘synthetic diamond’, a totally incorrect and misleading usage. These films are usually neither clear nor transparent when of significant thickness. Moreover, they are definitely not diamond, any more than graphite or charcoal could properly be designated ‘diamond’ even though all are forms of carbon.
Confusion also arises from three additional points, which may need clarification. When a crystal grower claims that his crystals have ‘excellent’ quality or are ‘flawless’, he does not mean that they are flawless by gemological standard; usually it means that he can see through the layers or perhaps even read print with the crystal set on the paper, which may not be difficult when the layer is only a fraction of a millimeter in thickness.
The second point involves the definition of ‘diamond’ which is strictly defined as the cubic form of carbon. There is also a hard hexagonal form of carbon, properly designated lonsdaleite ‘hexagonal diamond’ which is erroneous because it means ‘hexagonal cubic caron’. So in the diamond thin-film business ‘diamond’ may not always mean diamond, but may also mean lonsdaleite or amorphous carbon.
Finally, a statement such as ‘a growth rate of one inch per week has been achieved’ does not mean that one inch has been grown; it may mean only that one thousandth of one inch was grown in one-thousandth of a week, that is in ten minutes. But growth rates do not always scale up.
The best way to understand the present rather confusing situation is to consider briefly the high-and low-pressure techniques and the five groups of synthetic diamond products.
Synthetic High Pressure Diamond
The high pressure technique for growth of synthetic diamond was discovered by H Tracy Hall at General Electric in 1955, using temperatures about 2000°C (3623°F) and pressure over one million pounds per square inch. At first, only grit could be made; GE announced gem size crystals in 1970.
Group 1: Synthetic High Pressure Yellow Diamond
Yellow synthetic diamond, colored by traces of nitrogen absorbed from the air during the growth, is readily grown by using a variety of metal solvents; crystals over 12mm across and over 14 carats in weight have been reported. By growing several layers with several small crystals per layer at one time, synthetic diamond slices used as heat sinks for transistors and integrated circuits can be produced economically. Several companies have the capability of doing this, including De Beers, GE and Sumitomo. The gemological properties of such synthetic high pressure yellow diamond have been described for example by Shigley et.al (1987). Identification should present no serious problems.
Group II: Synthetic High Pressure Colorless and Blue Diamond
For the colorless product, nitrogen must be excluded, and boron is additionally used to obtain a blue color. In both instances, special conditions must be used, such as aluminum in the solvent to remove nitrogen. This makes it more difficult to grow many crystals at one time. The characteristics of the products have been discussed by Koivula and Fryer (1984), and Shigley et.al (19860, and identification would probably present no serious problems if and when routine production, and therefore, a standardized product should happen.
Colorless and blue synthetic diamonds suitable for faceting have, indeed, been grown only on an experimental basis so far, and one can estimate that cost of production is not very different from that of natural diamond. To put this statement into perspective, synthetic colored gemstones, such as flux grown emerald, ruby, and so on, appear to be viable at a cost of less than one-tenth that of the equivalent quality natural material, but experience has shown that the market is very restricted except at even lower prices.
Thin Film Carbon Deposition
Various low pressure techniques using carbon-containing gases such as methane or acetylene and temperatures of 1200°C (2192°F) or below are used to grow a variety of types of diamond and other carbon-containing films under non-equilibrium conditions. Even acetylene torches have been used. For reviews of thin film work, see DeVries (1987), Angus and Hayman (1988), and Bachman and Messier (1989).
Group III: Synthetic Polycrystalline Diamond Films
When conditions are carefully controlled, polycrystalline diamond film s can be grown quite rapidly to become a millimeter or more in thickness. When very thin, these would not be readily detected, even by a thermal probe, and would probably not serve any useful purpose in gemology. Weight gain would be negligible and the surface hardness would not be changed significantly.
This last statement may be surprising, but a scratch test applied to a very thin diamond film covering a soft material would merely result in distortion of the substrate, and tearing and detaching of the film. If the film is thick, so that it could give a diamond reaction on a thermal probe ad provide a hard surface for a soft material, it would be visible during a gemological investigation. Moreover, adhesion of such polycrystalline diamond film is extremely poor to substances other than silicon, silcon carbide (moissanite), or diamond itself.
Group IV: Synthetic Single Crystal Diamond Films
This type of film appears to be great concern to some, because it seems to provide the threat of increasing the size of a natural diamond. Single crystal diamond films can indeed be grown on diamond surface by suitable adjustments of the low pressure techniques. Yet, a curious phenomenon occurs: the film only seems to reach a certain thickness, depending on the techniques used. If one tries to force it to continue to grow, then it either stops, turn polycrystalline (when the remarks under Group III apply), or something else happens.
Such films often contain stacking faults and may then be not diamond but lonsdaleite. It is of course possible that someone may discover someday how to keep the films growing, but work on this topic has been underway for over 30 years; a solution just does not seem easy to find. Adhesion is a problem on materials other than those listed above.
One interesting possibility is that a very thin synthetic crystal blue diamond film coating could enhance the appearance of yellow cape-series diamonds. This has been done experimentally (see Fritisch, 1991). Such a film should be as easily detected as a thin blue lacquer layer, by standard gemological testing: the concentration of color in the surface layer can be seen by immersion even in water. The acceptability of such an overgrowth would depend on the nomenclature; it might well be decided that this must be called a ‘natural-synthetic composite diamond.’
Group V: Diamond-like Films
A wide variety of different films which are not diamond but are often so labelled can be deposited quite rapidly and to millimeter thickness by various modifications of the low pressure technique. Some of these are non-crystalline amorphous or glassy films. Some contain significant amounts of hydrogen, up to one hydrogen per carbon, and should then be called hydrocarbon films. Some are partly crystalline but, instead of containing only sp-3 bonding as does diamond, also contain some sp-2 bondings as does graphite. Some have stacking sequences leading to hexagonal lonsdaleite. The materials considered in this group do not have the cube symmetry of diamond.
Additional names that have been used include amorphous carbon, amorphous hydrocarbon, dense (hydro) carbon, hard or superhard carbon, and non-diamond carbon films. All of these names may be appropriate for some such films, but the name ‘diamond’ is definitely incorrect. The hardness may vary from less than 8 to over 9, the color may be black, grey, or near colorless (particularly if very thin), and adhesion is a problem on most materials. It is difficult to visualize any application of such films in the gem field.
The Lessons From Other Synthetics
It is worth examining briefly what happens when usable synthetic gemstones first arrived in the trade. The result was the same each time, whether the product was synthetic ruby in 1905, synthetic sapphire in 1910, synthetic star corundum in 1947, synthetic emerald in 1950, synthetic alexandrite in 1972, and so on. At first there was considerable apprehension, both with respect to the effect on the trade, and also with respect to the ability to distinguish the new synthetic from natural. Each time, this stage was followed by the realization that synthetic could be distinguished from the natural with little trouble, and that synthetic filled a different niche from the natural.
In each instance there was essentially no long term effect on the market for the natural material. It is perhaps worth repeating that synthetics have only been successful in their own niches at a price less than one tenth that of the natural material. Overgrowth of a synthetic over the surface of a natural gemstone has been possible since about 1960, when Lechleitner grew a thin layer of very dark green synthetic emerald over pale natural beryl performs. This has not been a successful product in the market place to date.
In conclusion, there is no significant impact to be expected from synthetic diamond, whether produced in bulk form by the high pressure technique or in the thin film form by the low pressure technique. As always, a steady improvement of growth technology must certainly be anticipated. Significant future breakthroughs are always a possibility and would then change the present status. But they should be of concern only when they happen.
For example, there is little likelihood of D flawless synthetic diamond in carat and larger sizes and at a production cost to make it viable as a synthetic as discussed above for many years to come. After all, someone might just discover next week a new diamond mine containing huge quantities of large flawless stones; while such a discovery is not impossible, it is merely highly improbable.
Jewelry
History & Technique from the Egyptians to the Present
By Guido Gregorietti
Chartwell Books, Inc
1979 ISBN 089009-231-1
Chartwell Books writes:
A jewel has many meanings. It is a work of art, an ornament denoting rank, a statement of dress, a treasure, a sign of power, an investment, an ethnic clue, an ostentation.
One of the most famous and dependable Parisian jewelers, whose base is in Place Vendome, makes it a professional rule never to reveal the identity of his customers. One exception was made, however, when the firm was put in charge of preparing the ceremonial crown for the Empress of Iran. It would have been difficult to keep it anonymous: 1469 diamonds, 36 rubies, as many emeralds and 105 pearls were mounted on the crown in Teheran, after a year’s work.
Why jewels are never enough to satisfy is a problem for anthropologists and psychologists to explain. A bouquet of 6000 diamonds was shown at the Great Exhibition of 1851 in London; perhaps satisfying enough? Between 1884 and 1917 the Tsar of Russia presented members of his family with fifty Easter eggs with surprises in them, created by the famous Faberge in enamel and precious stones.
If we pause to think of the quantity of jewels worked into gold dug up at Troy, in Mesopotamia, in Egypt and Peru, we see the ancients could compete favorably with modern craftsmen. Also—and a curious thing to have to admit with today’s technology—the ancients had techniques which no one since has known how to repeat.
The history of jewelry, too, has a certain amount of unknown meaning. It even sometimes has a superstitious aura of occult magic.
Guido Gregorietti’s narrative of the fabulous history of jewelry places it in context in the history of art, while interweaving many aspects of the evolution of culture.
About the author
Guido Gregorietti is the author of the Jewelry entry in the Encyclopedia Britannica, and was called upon to take part in judging the 1977 Diamond Award in New York.
By Guido Gregorietti
Chartwell Books, Inc
1979 ISBN 089009-231-1
Chartwell Books writes:
A jewel has many meanings. It is a work of art, an ornament denoting rank, a statement of dress, a treasure, a sign of power, an investment, an ethnic clue, an ostentation.
One of the most famous and dependable Parisian jewelers, whose base is in Place Vendome, makes it a professional rule never to reveal the identity of his customers. One exception was made, however, when the firm was put in charge of preparing the ceremonial crown for the Empress of Iran. It would have been difficult to keep it anonymous: 1469 diamonds, 36 rubies, as many emeralds and 105 pearls were mounted on the crown in Teheran, after a year’s work.
Why jewels are never enough to satisfy is a problem for anthropologists and psychologists to explain. A bouquet of 6000 diamonds was shown at the Great Exhibition of 1851 in London; perhaps satisfying enough? Between 1884 and 1917 the Tsar of Russia presented members of his family with fifty Easter eggs with surprises in them, created by the famous Faberge in enamel and precious stones.
If we pause to think of the quantity of jewels worked into gold dug up at Troy, in Mesopotamia, in Egypt and Peru, we see the ancients could compete favorably with modern craftsmen. Also—and a curious thing to have to admit with today’s technology—the ancients had techniques which no one since has known how to repeat.
The history of jewelry, too, has a certain amount of unknown meaning. It even sometimes has a superstitious aura of occult magic.
Guido Gregorietti’s narrative of the fabulous history of jewelry places it in context in the history of art, while interweaving many aspects of the evolution of culture.
About the author
Guido Gregorietti is the author of the Jewelry entry in the Encyclopedia Britannica, and was called upon to take part in judging the 1977 Diamond Award in New York.
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