Thursday, July 12, 2007
The Culture Of The GIA Synthetic Certificate Debate
Chaim Even-Zohar writes about the issues discussed at the GIA Symposium in San Diego + consumer confidence issues + FTC vs. industry governing bodies + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26152
SA's New Diamond Regulator Takes Shape
Polished Prices writes:
The South African government moved ahead this week with several key appointments to its state diamond regulatory body.
Among the appointments for the new regulator - in charge of licencing, the Kimberley Process and beneficiation - is Louis Selekane, current CEO of the South African Diamond Board, who will become chief executive.
Martin Mononela, previously chief director at the Department of Minerals and Energy, will act as general manager. According to Mononela, the boards of the State Diamond Trader as well as the regulator – each comprising of 16 civil and industry representatives – have already been appointed.
Based on the new South African Diamond legislation, 10% by value of the country’s diamond production must be made available to the State Diamond Trader. The government is currently in the process of appointing a State Trader, whose activities will be overseen but its own independent board of directors.
Licence holders applying for goods from the State Diamond Trader are required to polish and cut 80% of their supplies in South Africa. The remaining 20% is exempted from export duty, said Mononela.
“After personnel have been put in place at the trading body, the trading will begin," said Mononela, adding this could be as early as August 2007. “In terms of the law, the negotiations have been finalised with the producers,” he said.
The President is expected to promulgate the new legislation no later than August 2007.
More info @ http://www.polishedprices.com/article.shtml?ID=1000004502
The South African government moved ahead this week with several key appointments to its state diamond regulatory body.
Among the appointments for the new regulator - in charge of licencing, the Kimberley Process and beneficiation - is Louis Selekane, current CEO of the South African Diamond Board, who will become chief executive.
Martin Mononela, previously chief director at the Department of Minerals and Energy, will act as general manager. According to Mononela, the boards of the State Diamond Trader as well as the regulator – each comprising of 16 civil and industry representatives – have already been appointed.
Based on the new South African Diamond legislation, 10% by value of the country’s diamond production must be made available to the State Diamond Trader. The government is currently in the process of appointing a State Trader, whose activities will be overseen but its own independent board of directors.
Licence holders applying for goods from the State Diamond Trader are required to polish and cut 80% of their supplies in South Africa. The remaining 20% is exempted from export duty, said Mononela.
“After personnel have been put in place at the trading body, the trading will begin," said Mononela, adding this could be as early as August 2007. “In terms of the law, the negotiations have been finalised with the producers,” he said.
The President is expected to promulgate the new legislation no later than August 2007.
More info @ http://www.polishedprices.com/article.shtml?ID=1000004502
A Diamond District Far From 47th Street
Hilary Larson writes about Brugges and Antwerp + its international status as the center for diamonds and fashion + other viewpoints @ http://www.thejewishweek.com/news/newscontent.php3?artid=14252
Precious Stones Of The Future From The Laboratory
An insider (s) view + tips for students studying synthetic gemstone identification course (s).
(via The Journal of Gemmology, Vol.XVI, No.7, July 1979)
A report on M. Pierre Gilson’s talk
On the 11th October, 1978, a talk was given to members of the Association by M Pierre Gilson on ‘Precious Stones of the Future from the Laboratory’ in the Geological Museum Cinema Theatre, South Kensington. The theatre was full when the proceedings were opened and the speaker was introduced by the vice-chairman, Dr David Callaghan, FGA, who said M Gilson produced the very best that man could produce and was able to do in a relatively short time things which Nature took very much longer to achieve; his talent and the vast range of materials that he was producing were quite fantastic.
M Gilson’s talk then took the form of a running commentary no the hundred or so slides which he showed during the evening and he left few people in doubt about the progress made in the last fifty or sixty years. He reminded the audience that Verneuil was the first to make synthetic ruby and sapphire at the beginning of the century: with his relatively simple method he was able to produce a boule in one of several colors in a matter of three hours or so, and his synthetic corundum was soon used to make the jewels in watches.
In contrast, M Gilson’s company takes as long as nine months to grow synthetic emeralds. They start with a seed—synthetic material of the highest quality—and grow it as a non-stop process for nine months. A continuous supply of electricity is essential, because it is important to allow crystallization to take place at a constant temperature if good crystals are to be grown. Accordingly arrangements have been made to ensure that the company is guaranteed a supply of electricity privately in case there should be a failure in the public supply due to breakdown or perhaps a strike.
But it is not just a matter of having the right equipment and know how: experimentation also is necessary. Before success in making synthetic turquoise was achieved, thirty different phosphates had to be crystallized.
The equipment now used in the Gilson laboratories is very sophisticated and quite advanced. In order to study the size and formation of the tiny ‘beads’ which make up such gemstones as emeralds an electron microscope is used. A spectrophotometer is another essential piece of equipment, because it is important to be able to control absorption to within one part per million.
With synthetic emeralds M Gilson has found it beneficial to cut at a specific angle in relation to the seed crystal on which the new material has been grown. He used slides to explain that the main difference between synthetic and natural emerald lies in the nature of the inclusions. In the synthetic material the ‘veil’ is twisted, whereas in the natural stone it is straight. He added that Nature produced only one good emerald for every million crystals formed: in the laboratory it was essential to have a very much higher success rate. Emerald production in the Gilson laboratory takes precisely nine months, since, if you wait any longer, crystallization may have stopped. A simple—but impractical! –test to distinguish between natural and synthetic emerald was mentioned: if you heat it to one thousand degrees and it turns white when it cools, you know it is natural. He added that the hardness of emerald was affected by the extent of inclusions in a given stone.
Opal was next discussed. Opal is pure silica: it acts like a prism and the colors which can be seen are pure spectral colors. Gilson synthetic opals contain more pure colors than natural material because they contain more pure constituents. Laboratory production of opal calls for a very high temperature: natural opal is no longer being created because temperatures are not high enough. Even in the laboratory it is impossible to produce two identical opals. Production starts with the production of millions of tiny beads, each about 0.3 microns in diameter, and these eventually form the finished material. M Gilson’s most recent improvements involve the removal of all traces of water from synthetic opals, and this gets rid of cracks and helps to avoid some of the hazards associated with the natural material. With natural opals, it is interesting to note that material found at depth of more than six meters is often noticeably better than stones found near the surface.
Natural turquoise contains iron, and in some cases customers are disappointed when the iron turns green after a year or two. ‘Our own stones are pure turquoise, so this problem doesn’t arise’—but a process has now been developed so that iron can be introduced to the surface of synthetic turquoise.
With lapis, although pyrites (its inclusions) can be synthesized, M Gilson uses natural pyrites. ‘Each day nine hundred tons of natural pyrites are mined: I cannot compete with that!’ He is now successfully synthesizing coral and used calcite which is now being mined in France.
In answer to a question whether he could suggest any methods of testing stones to tell the difference between real and synthetic specimens, he said: ‘We work on developing new scientific products, but when it comes to identification you are the experts.’ Asked whether it was his intention to produce stones so similar to the natural product that they could not be detected, he replied: ‘We are not competing with Nature but merely trying to improve on it by producing more pure stones—more beautiful ones for the jeweler to work with.’
Mr Alec Farn asked if M Gilson had produced any emeralds without chromium but with the addition of vanadium, and M Gilson replied that he had not—and even if it was done, could the result be described as emerald?’ ‘If people want chromium in emerald, then why shouldn’t we give it to them?’
Offering a tip for improving opals, M Gilson said that if soaked over night in ethyl alcohol all moisture in the stone would be driven out and the color improved—but it was essential not to do this if the stone was a triplet! And in reply to an enquiry whether he had carried out any experiment on the jadeite family, he smiled and said: ‘Yes, we are working on this problem.’
When asked how long he had been trying to make synthetic stones before he had his first success, he said he took fifteen years to succeed with emerald, ten years with opal, and eight years with turquoise: and because of slow reactions and the length of time it took to grow a single crystal before it was known whether or not the experiment was a success, research was becoming more difficult and expensive. Some members of the audience were surprised when M Gilson mentioned that his main business was not the production of synthetic gemstones but the manufacture of about nine tons of ceramics each month for industrial use.
(via The Journal of Gemmology, Vol.XVI, No.7, July 1979)
A report on M. Pierre Gilson’s talk
On the 11th October, 1978, a talk was given to members of the Association by M Pierre Gilson on ‘Precious Stones of the Future from the Laboratory’ in the Geological Museum Cinema Theatre, South Kensington. The theatre was full when the proceedings were opened and the speaker was introduced by the vice-chairman, Dr David Callaghan, FGA, who said M Gilson produced the very best that man could produce and was able to do in a relatively short time things which Nature took very much longer to achieve; his talent and the vast range of materials that he was producing were quite fantastic.
M Gilson’s talk then took the form of a running commentary no the hundred or so slides which he showed during the evening and he left few people in doubt about the progress made in the last fifty or sixty years. He reminded the audience that Verneuil was the first to make synthetic ruby and sapphire at the beginning of the century: with his relatively simple method he was able to produce a boule in one of several colors in a matter of three hours or so, and his synthetic corundum was soon used to make the jewels in watches.
In contrast, M Gilson’s company takes as long as nine months to grow synthetic emeralds. They start with a seed—synthetic material of the highest quality—and grow it as a non-stop process for nine months. A continuous supply of electricity is essential, because it is important to allow crystallization to take place at a constant temperature if good crystals are to be grown. Accordingly arrangements have been made to ensure that the company is guaranteed a supply of electricity privately in case there should be a failure in the public supply due to breakdown or perhaps a strike.
But it is not just a matter of having the right equipment and know how: experimentation also is necessary. Before success in making synthetic turquoise was achieved, thirty different phosphates had to be crystallized.
The equipment now used in the Gilson laboratories is very sophisticated and quite advanced. In order to study the size and formation of the tiny ‘beads’ which make up such gemstones as emeralds an electron microscope is used. A spectrophotometer is another essential piece of equipment, because it is important to be able to control absorption to within one part per million.
With synthetic emeralds M Gilson has found it beneficial to cut at a specific angle in relation to the seed crystal on which the new material has been grown. He used slides to explain that the main difference between synthetic and natural emerald lies in the nature of the inclusions. In the synthetic material the ‘veil’ is twisted, whereas in the natural stone it is straight. He added that Nature produced only one good emerald for every million crystals formed: in the laboratory it was essential to have a very much higher success rate. Emerald production in the Gilson laboratory takes precisely nine months, since, if you wait any longer, crystallization may have stopped. A simple—but impractical! –test to distinguish between natural and synthetic emerald was mentioned: if you heat it to one thousand degrees and it turns white when it cools, you know it is natural. He added that the hardness of emerald was affected by the extent of inclusions in a given stone.
Opal was next discussed. Opal is pure silica: it acts like a prism and the colors which can be seen are pure spectral colors. Gilson synthetic opals contain more pure colors than natural material because they contain more pure constituents. Laboratory production of opal calls for a very high temperature: natural opal is no longer being created because temperatures are not high enough. Even in the laboratory it is impossible to produce two identical opals. Production starts with the production of millions of tiny beads, each about 0.3 microns in diameter, and these eventually form the finished material. M Gilson’s most recent improvements involve the removal of all traces of water from synthetic opals, and this gets rid of cracks and helps to avoid some of the hazards associated with the natural material. With natural opals, it is interesting to note that material found at depth of more than six meters is often noticeably better than stones found near the surface.
Natural turquoise contains iron, and in some cases customers are disappointed when the iron turns green after a year or two. ‘Our own stones are pure turquoise, so this problem doesn’t arise’—but a process has now been developed so that iron can be introduced to the surface of synthetic turquoise.
With lapis, although pyrites (its inclusions) can be synthesized, M Gilson uses natural pyrites. ‘Each day nine hundred tons of natural pyrites are mined: I cannot compete with that!’ He is now successfully synthesizing coral and used calcite which is now being mined in France.
In answer to a question whether he could suggest any methods of testing stones to tell the difference between real and synthetic specimens, he said: ‘We work on developing new scientific products, but when it comes to identification you are the experts.’ Asked whether it was his intention to produce stones so similar to the natural product that they could not be detected, he replied: ‘We are not competing with Nature but merely trying to improve on it by producing more pure stones—more beautiful ones for the jeweler to work with.’
Mr Alec Farn asked if M Gilson had produced any emeralds without chromium but with the addition of vanadium, and M Gilson replied that he had not—and even if it was done, could the result be described as emerald?’ ‘If people want chromium in emerald, then why shouldn’t we give it to them?’
Offering a tip for improving opals, M Gilson said that if soaked over night in ethyl alcohol all moisture in the stone would be driven out and the color improved—but it was essential not to do this if the stone was a triplet! And in reply to an enquiry whether he had carried out any experiment on the jadeite family, he smiled and said: ‘Yes, we are working on this problem.’
When asked how long he had been trying to make synthetic stones before he had his first success, he said he took fifteen years to succeed with emerald, ten years with opal, and eight years with turquoise: and because of slow reactions and the length of time it took to grow a single crystal before it was known whether or not the experiment was a success, research was becoming more difficult and expensive. Some members of the audience were surprised when M Gilson mentioned that his main business was not the production of synthetic gemstones but the manufacture of about nine tons of ceramics each month for industrial use.
Chrysocolla
Chemistry: Hydrous copper silicate (variable).
Crystal system: Monoclinic; cryptocrystalline massive.
Color: Semi-translucent to opaque; green to blue; chrysocolla quartz; chrysocolla opal; Eilat stone: mixture of chrysocolla, turquoise, malachite and other copper minerals.
Hardness: 2 - 4
Cleavage: None; Fracture: even.
Specific gravity: 2.0 – 2.4; Eilat stone: 2.8 – 3.2
Refractive index: 1.50 approx; Eilat stone: 1.46 – 1.57 (varies with composition)
Luster: Vitreous.
Dispersion: -
Dichroism: -
Occurrence: Zone of weathering in copper lodes and deposits; Chile, DR Congo; Russia, USA, Peru, Australia.
Notes
Porous; R.I and heavy liquids can damage; may impregnate quartz/opal; color may be ‘mountain green, bluish green, sky blue, turquoise blue, often with an opal/enamel-like texture; Eilat stone found near Eilat, Gulf of Aquaba in Red Sea; mottled blue and green; contain copper carbonate malachite; reacts vigorously with acids; cut mainly cabochons.
Crystal system: Monoclinic; cryptocrystalline massive.
Color: Semi-translucent to opaque; green to blue; chrysocolla quartz; chrysocolla opal; Eilat stone: mixture of chrysocolla, turquoise, malachite and other copper minerals.
Hardness: 2 - 4
Cleavage: None; Fracture: even.
Specific gravity: 2.0 – 2.4; Eilat stone: 2.8 – 3.2
Refractive index: 1.50 approx; Eilat stone: 1.46 – 1.57 (varies with composition)
Luster: Vitreous.
Dispersion: -
Dichroism: -
Occurrence: Zone of weathering in copper lodes and deposits; Chile, DR Congo; Russia, USA, Peru, Australia.
Notes
Porous; R.I and heavy liquids can damage; may impregnate quartz/opal; color may be ‘mountain green, bluish green, sky blue, turquoise blue, often with an opal/enamel-like texture; Eilat stone found near Eilat, Gulf of Aquaba in Red Sea; mottled blue and green; contain copper carbonate malachite; reacts vigorously with acids; cut mainly cabochons.
Wednesday, July 11, 2007
Sightholders Losses May Ignite A Banking Revolt
Chaim Even-Zohar writes about sightholder concerns + the credit business + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26181
Examination Of Maxixe-type Blue And Green Beryl
Only a very few know about Maxixe-type beryl (s), and often they are confused for aquamarine, iolite or even quartz. I have seen gem dealers getting puzzled when they have to deal with lots, and eventually they are sold as something else. You don't want to make god-like statement (s) when you don't have comparison stones or at times you go through 'momentary autism'--you just go blank/inert. Only a sophisticated lab with experienced staff will be able to recognize the tell-tale signs. Many labs do not have sample (s) of Maxixe-type beryl (s) for comparsion purposes so they get confused and misidentify them. At times it's like two blind walking the street (s).
(via The Journal of Gemmology, Vol.13, No.8, October 1973) K Nassau / D L Wood writes:
Abstract
Blue Maxixe beryl, kept in the dark since 1917, and current blue and green beryl showing similar characteristics have been examined b absorption spectroscopy, gamma ray spectroscopy, chemical analysis, and light, heat and irradiation treatments. All three show an anomalous dichroism (the ordinary ray is more blue than the extraordinary ray, while in aquamarine the reverse is true) and an unusual narrow band spectrum in the red and yellow regions. In all three cases the color is bleached by exposure to daylight or on heating and can be recovered by neutron or gamma ray irradiation. A color center not involving a transition metal such as Fe, Co, Cu, etc. is indicated. Examination of 23 faceted ‘sapphire’ blue beryl gemstones by gamma ray spectroscopy indicates that three had definitely been colored by neutron irradiation; the others may or may not have been treated by irradiation.
Introduction
About 1917 blue beryl was found in the Maxixe mine in Minas Gerais, Brazil, which had the following unusual properties: it showed a strong anomalous dichroism, a narrow band absorption spectrum for the ordinary ray which produces a pronounced ‘sapphire’ or ‘cobalt’ blue (distinctly different from the blue of aquamarine beryl); and the color faded on exposure to light. These and other properties were reported in 1933 and 1935. We consider any beryl to be ‘Maxixe-type’ beryl if it shows these three unusual properties: dichroism with blue in the ordinary ray; narrow-banded absorptions in the ordinary ray spectrum; and bleaching on exposure to light or heat. Some recent material of this type has become available, and our attention was drawn to the unusual absorption spectrum by Mr R Crowningshield.
Experimental
We have examined in detail the following: a piece of the original Maxixe find that has been kept from extended exposure to light since 1917, courtesy of Mr B W Anderson; 23 specimens of currently commercially available deep blue faceted stones (ranging from four to ten carats in weight) as well as blue rough, from an unspecified locality said to be in Brazil; and three dark green stones and some dark green rough, possibly from the same current locality. All exhibit the three properties just mentioned. Although there were some minor differences, all these specimens showed pronounced blue/colorless, blue/pale pink, or green/yellow dichroism with a similar characteristic w spectrum in the 5000 to 7500 Angstrom region.
Permission was obtained to expose to light four current deep blue stones, current deep blue and green rough, and part of the old Maxixe rough (either to daylight with intermittent sun or to a 100-watt frosted tungsten light bulb at a distance of six inches in an air-conditioned room) After one week all had faded significantly, ending with only about half of the original color or less. The bleaching was then completed by heating to a maximum of 235º (450ºF) for 30 minutes, resulting in a yellow or pale pink color. By comparison, aquamarine is customarily heated to a much higher temperature (400ºC - 750ºF) to improve the color, which remains stable to light.
Examination of all the specimens by gamma-ray spectroscopy using a lithium drifted germanium detector indicated in three of the faceted stones the presence of a small amount of Caesium-134, a radioactive species with a half life of 2 years. This is absent in nature, but produced by neutron irradiation of natural Caesium-133 in the specimens. These stones must therefore have been treated by neutron irradiation. The other specimens did not show this behavior and have probably not been irradiated with neutrons. On heating one of the partially bleached cut stones to 150ºC for 30 minutes there was no significant further change in color. However, after 30 minutes at 200ºC (about 400ºF) only a very pale pink color remained. Neutron irradiation (15 minutes at 10¹³ neutrons/cm²/sec) now returned the stone to a blue color even deeper than its original color. Another similar stone (blue/pale pink dichroism), when heated by Mr R Crowningshield, bleached completely to pale pink in less than 30 minutes at 95ºC (200ºF). This stone was exposed to gamma rays (2 x 107 rads from Cobalt 60) and also turned deep blue. This gamma ray irradiation does not leave any evidence of treatment, producing the usual characteristic w spectrum. As expected from the case of heat bleaching, this stone also bleached very rapidly in light (significantly in only 15 hours).
The green material, when bleached to a deep yellow by sunlight, could be returned to green by neutron irradiation, to a weak blue/green by X-rays, but was hardly changed by gamma rays from Cobalt-60. The recolored material (both blue and green) could be bleached again by light. The green could also be changed to yellow by a 30-minute heat treatment at 150ºC, while heating to 400ºC removed the yellow color as was previously noted in an ordinary yellow beryl; neutron irradiation returned this colorless material to green.
Analysis showed a high iron content in the green material (about 0.2%), but essentially none in the old Maxixe sample (0.000X%). This is consistent with the spectral evidence that the deep yellow component is due to Fe3+ in the octahedral Al site and indicates that Fe is not involved in the narrow banded w spectrum. Other transition metals such as Co, Cu, etc. are essentially absent. Since the blue material can be bleached by exposure to light or quite low temperatures and recovered by irradiation, a color center not involving a transition metal ion is indicated. The minor differences in the spectra may well be associated with differences in the total alkali content, the old Maxixe being high (about 2%), the green low (less than 0.1%).
Neutron irradiation was also tried on several of the beryl specimens used in our previous study. One of these, a colorless beryl showed a faint blue color after irradiation, and on examination showed a weak w spectrum of the Maxixe-type. Accordingly it appears that not any beryl can be irradiated to give a Maxixe-type color, but neither does it appear to be necessary to have material from a unique location. Investigation on this point is continuing.
Conclusions
There is some variation in spectrum, iron content, alkali content, color, and rate of bleaching by either light or heat. Nevertheless, in contrast to the many ordinary varieties of beryl known over the centuries, these specimens show sufficient similarity to merit a common designation, and we have used the term ‘Maxixe-type’ based on the first reported occurrence. At present there is not enough information to decide if this type of material originates from one or several localities. It appears that the color of some of this material may be as originally found, although some material has definitely been neutron irradiated either to form the color, to improve the color, or to return color which has been bleached by exposure to light or to heat. Some or all of the rest may have been colored by gamma rays.
Based on the observations here reported we believe that any blue or green beryl (particularly if the blue color is of ‘sapphire’ type) showing anomalous dichroism with the blue color in the ordinary ray and sharp absorption bands for the ordinary ray in the 5000 to 7500 Angstrom region should be designated as ‘Maxixe-type’. Such a beryl will face, either on exposure to light or on heating. Such a beryl may or may not have been irradiated with neutrons or with gamma rays. It is in fact not possible to determine whether a given stone has been treated or how fast it will fade.
In the words of Mr Crowningshield ‘potential buyers should be alerted to the possibility that any stone of this type, which they consider, may fade too rapidly to be a satisfactory jewelry stone.’
Appendix
A note on color centers
Most of the color in gems and minerals is caused by unpaired electrons in major ingredients such as the copper in malachite and turquoise, or in impurities such as the chromium in ruby and emerald or the iron in aquamarine and citrine. Alternatively there is color caused by physical structure, as in opal and labradorite (the optical diffraction grating effect).
But in some materials, where there is no such color causing ingredient or physical structure present, it is possible for ‘color centers’ to cause a variety of colors. Color centers have been studied intensively, but only few have been understood. Frequently this involves a vacancy (omitted atom) or some other type of defect (sometimes an impurity) which can hold (but does not of itself possess) an unpaired electron.
Examples of color centers occur in halite or sylvite (made purple to black by various treatments), fluorite (green, purple, etc.) and smoky quartz. A frequent characteristic of color centers is that exposure to light or to relatively low temperatures may permit the unpaired electrons to pair off, thus removing the color. Irradiation by X-rays, neutrons, or some other form of penetrating radiation may cause the color to return by unpairing the electrons again. An unusual, only partly understood color center is involved in the amethyst form of quartz which also contains iron as an impurity. Amethyst is turned yellow or green by heat, and can be recolored with X-ray irradiation. However not just any quartz colored green or yellow with iron will go to amethyst with irradiation—some specific defect must still be associated with the iron impurity. Synthetic quartz containing iron must be grown in one specific direction to produce this specific color center and enable amethyst to be produced on subsequent X-ray irradiation. The color of amethyst is unusually stable for a color center, although it will fade over a period of many years or in hours at 400 to 600ºC. The relative ease with which the color is produced by X-rays is consistent with this stability to light and to heat.
In the case of the deep blue beryl there does not seem to be any specific impurity present. It is likely therefore that a vacancy is involved which can hold an unpaired electron. The relative ease of fading implies that the electrons pair off readily, and the difficulty of returning the color is consistent with this instability.
(via The Journal of Gemmology, Vol.13, No.8, October 1973) K Nassau / D L Wood writes:
Abstract
Blue Maxixe beryl, kept in the dark since 1917, and current blue and green beryl showing similar characteristics have been examined b absorption spectroscopy, gamma ray spectroscopy, chemical analysis, and light, heat and irradiation treatments. All three show an anomalous dichroism (the ordinary ray is more blue than the extraordinary ray, while in aquamarine the reverse is true) and an unusual narrow band spectrum in the red and yellow regions. In all three cases the color is bleached by exposure to daylight or on heating and can be recovered by neutron or gamma ray irradiation. A color center not involving a transition metal such as Fe, Co, Cu, etc. is indicated. Examination of 23 faceted ‘sapphire’ blue beryl gemstones by gamma ray spectroscopy indicates that three had definitely been colored by neutron irradiation; the others may or may not have been treated by irradiation.
Introduction
About 1917 blue beryl was found in the Maxixe mine in Minas Gerais, Brazil, which had the following unusual properties: it showed a strong anomalous dichroism, a narrow band absorption spectrum for the ordinary ray which produces a pronounced ‘sapphire’ or ‘cobalt’ blue (distinctly different from the blue of aquamarine beryl); and the color faded on exposure to light. These and other properties were reported in 1933 and 1935. We consider any beryl to be ‘Maxixe-type’ beryl if it shows these three unusual properties: dichroism with blue in the ordinary ray; narrow-banded absorptions in the ordinary ray spectrum; and bleaching on exposure to light or heat. Some recent material of this type has become available, and our attention was drawn to the unusual absorption spectrum by Mr R Crowningshield.
Experimental
We have examined in detail the following: a piece of the original Maxixe find that has been kept from extended exposure to light since 1917, courtesy of Mr B W Anderson; 23 specimens of currently commercially available deep blue faceted stones (ranging from four to ten carats in weight) as well as blue rough, from an unspecified locality said to be in Brazil; and three dark green stones and some dark green rough, possibly from the same current locality. All exhibit the three properties just mentioned. Although there were some minor differences, all these specimens showed pronounced blue/colorless, blue/pale pink, or green/yellow dichroism with a similar characteristic w spectrum in the 5000 to 7500 Angstrom region.
Permission was obtained to expose to light four current deep blue stones, current deep blue and green rough, and part of the old Maxixe rough (either to daylight with intermittent sun or to a 100-watt frosted tungsten light bulb at a distance of six inches in an air-conditioned room) After one week all had faded significantly, ending with only about half of the original color or less. The bleaching was then completed by heating to a maximum of 235º (450ºF) for 30 minutes, resulting in a yellow or pale pink color. By comparison, aquamarine is customarily heated to a much higher temperature (400ºC - 750ºF) to improve the color, which remains stable to light.
Examination of all the specimens by gamma-ray spectroscopy using a lithium drifted germanium detector indicated in three of the faceted stones the presence of a small amount of Caesium-134, a radioactive species with a half life of 2 years. This is absent in nature, but produced by neutron irradiation of natural Caesium-133 in the specimens. These stones must therefore have been treated by neutron irradiation. The other specimens did not show this behavior and have probably not been irradiated with neutrons. On heating one of the partially bleached cut stones to 150ºC for 30 minutes there was no significant further change in color. However, after 30 minutes at 200ºC (about 400ºF) only a very pale pink color remained. Neutron irradiation (15 minutes at 10¹³ neutrons/cm²/sec) now returned the stone to a blue color even deeper than its original color. Another similar stone (blue/pale pink dichroism), when heated by Mr R Crowningshield, bleached completely to pale pink in less than 30 minutes at 95ºC (200ºF). This stone was exposed to gamma rays (2 x 107 rads from Cobalt 60) and also turned deep blue. This gamma ray irradiation does not leave any evidence of treatment, producing the usual characteristic w spectrum. As expected from the case of heat bleaching, this stone also bleached very rapidly in light (significantly in only 15 hours).
The green material, when bleached to a deep yellow by sunlight, could be returned to green by neutron irradiation, to a weak blue/green by X-rays, but was hardly changed by gamma rays from Cobalt-60. The recolored material (both blue and green) could be bleached again by light. The green could also be changed to yellow by a 30-minute heat treatment at 150ºC, while heating to 400ºC removed the yellow color as was previously noted in an ordinary yellow beryl; neutron irradiation returned this colorless material to green.
Analysis showed a high iron content in the green material (about 0.2%), but essentially none in the old Maxixe sample (0.000X%). This is consistent with the spectral evidence that the deep yellow component is due to Fe3+ in the octahedral Al site and indicates that Fe is not involved in the narrow banded w spectrum. Other transition metals such as Co, Cu, etc. are essentially absent. Since the blue material can be bleached by exposure to light or quite low temperatures and recovered by irradiation, a color center not involving a transition metal ion is indicated. The minor differences in the spectra may well be associated with differences in the total alkali content, the old Maxixe being high (about 2%), the green low (less than 0.1%).
Neutron irradiation was also tried on several of the beryl specimens used in our previous study. One of these, a colorless beryl showed a faint blue color after irradiation, and on examination showed a weak w spectrum of the Maxixe-type. Accordingly it appears that not any beryl can be irradiated to give a Maxixe-type color, but neither does it appear to be necessary to have material from a unique location. Investigation on this point is continuing.
Conclusions
There is some variation in spectrum, iron content, alkali content, color, and rate of bleaching by either light or heat. Nevertheless, in contrast to the many ordinary varieties of beryl known over the centuries, these specimens show sufficient similarity to merit a common designation, and we have used the term ‘Maxixe-type’ based on the first reported occurrence. At present there is not enough information to decide if this type of material originates from one or several localities. It appears that the color of some of this material may be as originally found, although some material has definitely been neutron irradiated either to form the color, to improve the color, or to return color which has been bleached by exposure to light or to heat. Some or all of the rest may have been colored by gamma rays.
Based on the observations here reported we believe that any blue or green beryl (particularly if the blue color is of ‘sapphire’ type) showing anomalous dichroism with the blue color in the ordinary ray and sharp absorption bands for the ordinary ray in the 5000 to 7500 Angstrom region should be designated as ‘Maxixe-type’. Such a beryl will face, either on exposure to light or on heating. Such a beryl may or may not have been irradiated with neutrons or with gamma rays. It is in fact not possible to determine whether a given stone has been treated or how fast it will fade.
In the words of Mr Crowningshield ‘potential buyers should be alerted to the possibility that any stone of this type, which they consider, may fade too rapidly to be a satisfactory jewelry stone.’
Appendix
A note on color centers
Most of the color in gems and minerals is caused by unpaired electrons in major ingredients such as the copper in malachite and turquoise, or in impurities such as the chromium in ruby and emerald or the iron in aquamarine and citrine. Alternatively there is color caused by physical structure, as in opal and labradorite (the optical diffraction grating effect).
But in some materials, where there is no such color causing ingredient or physical structure present, it is possible for ‘color centers’ to cause a variety of colors. Color centers have been studied intensively, but only few have been understood. Frequently this involves a vacancy (omitted atom) or some other type of defect (sometimes an impurity) which can hold (but does not of itself possess) an unpaired electron.
Examples of color centers occur in halite or sylvite (made purple to black by various treatments), fluorite (green, purple, etc.) and smoky quartz. A frequent characteristic of color centers is that exposure to light or to relatively low temperatures may permit the unpaired electrons to pair off, thus removing the color. Irradiation by X-rays, neutrons, or some other form of penetrating radiation may cause the color to return by unpairing the electrons again. An unusual, only partly understood color center is involved in the amethyst form of quartz which also contains iron as an impurity. Amethyst is turned yellow or green by heat, and can be recolored with X-ray irradiation. However not just any quartz colored green or yellow with iron will go to amethyst with irradiation—some specific defect must still be associated with the iron impurity. Synthetic quartz containing iron must be grown in one specific direction to produce this specific color center and enable amethyst to be produced on subsequent X-ray irradiation. The color of amethyst is unusually stable for a color center, although it will fade over a period of many years or in hours at 400 to 600ºC. The relative ease with which the color is produced by X-rays is consistent with this stability to light and to heat.
In the case of the deep blue beryl there does not seem to be any specific impurity present. It is likely therefore that a vacancy is involved which can hold an unpaired electron. The relative ease of fading implies that the electrons pair off readily, and the difficulty of returning the color is consistent with this instability.
Charoite
Chemistry: Calcium potassium silicate with hydroxyl and fluorite.
Crystal system: Rock; massive.
Color: Semi-translucent to opaque; various shades of purple (Mn and / or Fe); may be solid color, banded, streaky purple and white, or fibrous (possibly containing black, gray or brownish orange areas).
Hardness: 5 - 6
Cleavage: None; Fracture: splintery to granular.
Specific gravity: 2.68
Refractive index: 1.55 (mean).
Luster: Vitreous, if well polished.
Dispersion: -
Dichroism: -
Occurrence: Siberia (Russia), NW of Alden.
Notes
Decorative ornamental material (distinctive structure); discovered in 1976 along the Charo River, northeast of Lake Baikal; purplish rock may contain radiating greenish black needles of Agirine augite (a pyroxene); yellowish to orangy prismatic crystals (Tipaskite); whitish green patches of microcline feldspar and other minerals; flouorescence: inert but feldspar may glow dull red; beads, carvings.
Crystal system: Rock; massive.
Color: Semi-translucent to opaque; various shades of purple (Mn and / or Fe); may be solid color, banded, streaky purple and white, or fibrous (possibly containing black, gray or brownish orange areas).
Hardness: 5 - 6
Cleavage: None; Fracture: splintery to granular.
Specific gravity: 2.68
Refractive index: 1.55 (mean).
Luster: Vitreous, if well polished.
Dispersion: -
Dichroism: -
Occurrence: Siberia (Russia), NW of Alden.
Notes
Decorative ornamental material (distinctive structure); discovered in 1976 along the Charo River, northeast of Lake Baikal; purplish rock may contain radiating greenish black needles of Agirine augite (a pyroxene); yellowish to orangy prismatic crystals (Tipaskite); whitish green patches of microcline feldspar and other minerals; flouorescence: inert but feldspar may glow dull red; beads, carvings.
How To Learn The Art Of Buying Art
Ashoke Nag writes about the do's and dont's, and how to ensure the piece of art harbors the essential elements + other viewpoints @ http://economictimes.indiatimes.com/quickies/2188328.cms
The Pirates’ Code
James Surowiecki writes about pirate ships and the simple constitutions + the link between pirate governance and CEO leadership @ http://www.newyorker.com/online/2007/07/09/070709on_onlineonly_surowiecki
I think James Surowiecki was spot on.
The New Gold Rush
Do you think gold mining is any different from gem mining? The local/foreign godfather (s) will always exploit the miner (s) one way or the other, and the loser (s) will be always the poor locals.
(via AP/Bangkok Post, July 10, 2007) Jonny Hogg writes:
For 12 years, Lauren Rakotondramara has been panning for gold on the banks of the Ikopa river in the dry western grasslands of this Indian Ocean island. For hours each day, he digs sand, places it in a panning dish made from an old oil drum lid and swirls it gently in the water, hoping tiny flecks of heavier gold will remain when the grit is washed away.
Rakotondramara scrounges together a gramme and a half of the precious metal a week. In the village market, he gets about $19 a gramme, so his takings come to four times the national average weekly wage.
“Every day my body aches from my work but if luck is with me and I find a lof of gold I can make good money,” the thin 57 year old said.
Rakotondramara is part of an innovative pilot project the government hopes will help it develop the gold industry in Madagascar, the ninth poorest country in the world, as well as allow workers like Rakotodramara to earn more from their labors—and free some from situations akin to indentured labor.
Madagascar has been known for its wildlife, not its mining. It has no formal gold industry, although there has been some large-scale mining, mostly controlled by French syndicates. More than 500000 small-scale miners like Rakotondramara have been operating clandestinely, risking harassment from authorities and price fixing on the black markets.
Under new laws that came into force in December, gold panners and collectors must register with the government and pay for permits. Funds raised from the permits go to local communities to fund infrastructure and development.
Johary Andriamanantena, director of the Gold Agency, the government agency that issues all mining permits, said the plan was being piloted among about 10000 miners in about 15 villages. He hoped to bring about 70 percent of all small scale miners in the country into the programme by next year.
“We don’t even know how much gold there is in Madagascar because before the industry was informal,” Andriamanantena said.
“We know that need a gold refinery in Magagascar to maximise profits for the country and we are hoping that a private investor from abroad will build one next year. The problem at the moment is that we have no statistics to show productivity or capacity, which is what investors want. By next year we will have these so the situation will be different,” he said.
“At the moment the price of gold here is lower than the global price,” Andriamanantena said. “With the new system we will publish international gold prices, so collectors (miners) will be able to get more for the gold that they sell.”
Gold on international markets is now at more than $600 a troy ounce (31 grammes). In Antanimbary, 300 km west of the capital, Antananarivo, each miner and panner pays $1.50 a year for a permit and buyers pay $50 a year to make purchases in the area. Miners and buyers will be taxed as well. Most miners have expressed happiness with going legal.
“Before this new law we had to hide when we worked and people caused us problems. Now, no one can cause me any problems and I can do my work openly. I can also get a better price for my gold,” Rakotondramara said.
Already, 1383 gold panners and miners, as well as 55 buyers have registered. A new school and four wells have been built and electric lighting for the main streeet installed, all with the money raised from permits.
According to Ranaivo Nonot, from NGO Green, a local development agency assisting the project, the local mayor’s budget for the area has tripled to about $7800.
“I had to show when I started this pilot project that I was reducing rural poverty,” Nonot. “You just have to look at things atht the village can afford now to know that we are being successful.”
NGO Green is funded by the World Bank which is helping with the implementation of the new law and teaching the local communities how the system will work. Tom Cushman works as a mining consultant for the World Bank. He wears loud shirts and he drives a hard bargain. After hours of checking the quality and quantity of the gold in Antanimbary market, he buys over a kilogramme.
“I’m trying to set up a model to show that it is possible to buy gold directly from the lowest level….and bring it all the way to the international market. This gold directly benefits the community, they are making a profit from it. Also, the people mining it and panning it are now part of the national economy. Before they were illegal and could be exploited, now they have a vested interest in the development of their country and they are protected by law.”
With the rough terrain unsuitable for agriculture and the tough stringy grass unpalatable for zebu, a type of cow aht is the most common livestock in the country, 80 percent of the Antanimbary relies on gold to generate an income.
Officials hope the new system will help wipe out exploitation. Now many of those digging or panning for gold sell only to their bosses. They are often forced to borrow money from the boses to live and in some cases entire families, including children, work on the mines to help pay off debt.
Some distance from the river, in the hills above the village, Randriananrivo, aged 62, who did not wish to give his full name, works at a shaft mine. The site is wind-swept and hot, littered with old shafts cut into the red earth. Thirty workers, some with families, live there in simple huts made from dried grass.
“I came here with no money,” Randriananarivo said. “My bos paid for my good and transport and I must sell my gold to him. He has taken my identity card so I cannot easily leave. If I cannot pay him back at the end of my contract he will give me more food and I must continue to work. But the food is expensive, maybe 50 percent more expensive than in the market, and we must pay someone to bring it to the mine site. Everyone here is in debt to their boss. We have to work to pay him back otherwise we’ll never leave.”
Randriananarivo said they received a fair price for the gold they mined but when asked about safety, he laughed and shook his head.
“We asked for oxygen so we could breathe properly in the mine but our patron said no, we owed him money so we must work,” he said.
According to miners, two people died at the site last year in mining accidents. Jean Jacques Rakotomavo, deputy mayor of Antanimbary, acknowledges that the exploitation and the safety fo the miners are two major problems they have not yet brought under control.
Rakotomavo said wealthy gold buyers, who are part of the new plan, are continuing to loan money to workers. As part of the loan they will pay for the worker’s mining permit.
“I know many people are in debt to rich people here. It’s not right but that’s the way it is. We try and control it but it’s difficult. If we can crack down on these rich people, those in debt won’t be able to work here and they’ll sill be in debt. I don’t think everything that is happening here is good, but we are at the very beginning and we will overcome these problems.”
(via AP/Bangkok Post, July 10, 2007) Jonny Hogg writes:
For 12 years, Lauren Rakotondramara has been panning for gold on the banks of the Ikopa river in the dry western grasslands of this Indian Ocean island. For hours each day, he digs sand, places it in a panning dish made from an old oil drum lid and swirls it gently in the water, hoping tiny flecks of heavier gold will remain when the grit is washed away.
Rakotondramara scrounges together a gramme and a half of the precious metal a week. In the village market, he gets about $19 a gramme, so his takings come to four times the national average weekly wage.
“Every day my body aches from my work but if luck is with me and I find a lof of gold I can make good money,” the thin 57 year old said.
Rakotondramara is part of an innovative pilot project the government hopes will help it develop the gold industry in Madagascar, the ninth poorest country in the world, as well as allow workers like Rakotodramara to earn more from their labors—and free some from situations akin to indentured labor.
Madagascar has been known for its wildlife, not its mining. It has no formal gold industry, although there has been some large-scale mining, mostly controlled by French syndicates. More than 500000 small-scale miners like Rakotondramara have been operating clandestinely, risking harassment from authorities and price fixing on the black markets.
Under new laws that came into force in December, gold panners and collectors must register with the government and pay for permits. Funds raised from the permits go to local communities to fund infrastructure and development.
Johary Andriamanantena, director of the Gold Agency, the government agency that issues all mining permits, said the plan was being piloted among about 10000 miners in about 15 villages. He hoped to bring about 70 percent of all small scale miners in the country into the programme by next year.
“We don’t even know how much gold there is in Madagascar because before the industry was informal,” Andriamanantena said.
“We know that need a gold refinery in Magagascar to maximise profits for the country and we are hoping that a private investor from abroad will build one next year. The problem at the moment is that we have no statistics to show productivity or capacity, which is what investors want. By next year we will have these so the situation will be different,” he said.
“At the moment the price of gold here is lower than the global price,” Andriamanantena said. “With the new system we will publish international gold prices, so collectors (miners) will be able to get more for the gold that they sell.”
Gold on international markets is now at more than $600 a troy ounce (31 grammes). In Antanimbary, 300 km west of the capital, Antananarivo, each miner and panner pays $1.50 a year for a permit and buyers pay $50 a year to make purchases in the area. Miners and buyers will be taxed as well. Most miners have expressed happiness with going legal.
“Before this new law we had to hide when we worked and people caused us problems. Now, no one can cause me any problems and I can do my work openly. I can also get a better price for my gold,” Rakotondramara said.
Already, 1383 gold panners and miners, as well as 55 buyers have registered. A new school and four wells have been built and electric lighting for the main streeet installed, all with the money raised from permits.
According to Ranaivo Nonot, from NGO Green, a local development agency assisting the project, the local mayor’s budget for the area has tripled to about $7800.
“I had to show when I started this pilot project that I was reducing rural poverty,” Nonot. “You just have to look at things atht the village can afford now to know that we are being successful.”
NGO Green is funded by the World Bank which is helping with the implementation of the new law and teaching the local communities how the system will work. Tom Cushman works as a mining consultant for the World Bank. He wears loud shirts and he drives a hard bargain. After hours of checking the quality and quantity of the gold in Antanimbary market, he buys over a kilogramme.
“I’m trying to set up a model to show that it is possible to buy gold directly from the lowest level….and bring it all the way to the international market. This gold directly benefits the community, they are making a profit from it. Also, the people mining it and panning it are now part of the national economy. Before they were illegal and could be exploited, now they have a vested interest in the development of their country and they are protected by law.”
With the rough terrain unsuitable for agriculture and the tough stringy grass unpalatable for zebu, a type of cow aht is the most common livestock in the country, 80 percent of the Antanimbary relies on gold to generate an income.
Officials hope the new system will help wipe out exploitation. Now many of those digging or panning for gold sell only to their bosses. They are often forced to borrow money from the boses to live and in some cases entire families, including children, work on the mines to help pay off debt.
Some distance from the river, in the hills above the village, Randriananrivo, aged 62, who did not wish to give his full name, works at a shaft mine. The site is wind-swept and hot, littered with old shafts cut into the red earth. Thirty workers, some with families, live there in simple huts made from dried grass.
“I came here with no money,” Randriananarivo said. “My bos paid for my good and transport and I must sell my gold to him. He has taken my identity card so I cannot easily leave. If I cannot pay him back at the end of my contract he will give me more food and I must continue to work. But the food is expensive, maybe 50 percent more expensive than in the market, and we must pay someone to bring it to the mine site. Everyone here is in debt to their boss. We have to work to pay him back otherwise we’ll never leave.”
Randriananarivo said they received a fair price for the gold they mined but when asked about safety, he laughed and shook his head.
“We asked for oxygen so we could breathe properly in the mine but our patron said no, we owed him money so we must work,” he said.
According to miners, two people died at the site last year in mining accidents. Jean Jacques Rakotomavo, deputy mayor of Antanimbary, acknowledges that the exploitation and the safety fo the miners are two major problems they have not yet brought under control.
Rakotomavo said wealthy gold buyers, who are part of the new plan, are continuing to loan money to workers. As part of the loan they will pay for the worker’s mining permit.
“I know many people are in debt to rich people here. It’s not right but that’s the way it is. We try and control it but it’s difficult. If we can crack down on these rich people, those in debt won’t be able to work here and they’ll sill be in debt. I don’t think everything that is happening here is good, but we are at the very beginning and we will overcome these problems.”
Tuesday, July 10, 2007
Memoirs Of A Geisha
Memorable quote (s) from the movie:
You cannot say to the sun, more sun or to the rain, less rain. To a man, geisha can only be half a wife. We are the wives of nightfall. And yet, to learn kindness after so much unkindness, to understand that a little girl with more courage than she knew, would find her prayers were answered, can that not be called happiness? After all these are not the memoirs of an empress, nor of a queen. These are memoirs of another kind. She paints her face to hide her face. Her eyes are deep water. It is not for Geisha to want. It is not for geisha to feel. Geisha is an artist of the floating world. She dances, she sings. She entertains you, whatever you want. The rest is shadows, the rest is secret.
You cannot say to the sun, more sun or to the rain, less rain. To a man, geisha can only be half a wife. We are the wives of nightfall. And yet, to learn kindness after so much unkindness, to understand that a little girl with more courage than she knew, would find her prayers were answered, can that not be called happiness? After all these are not the memoirs of an empress, nor of a queen. These are memoirs of another kind. She paints her face to hide her face. Her eyes are deep water. It is not for Geisha to want. It is not for geisha to feel. Geisha is an artist of the floating world. She dances, she sings. She entertains you, whatever you want. The rest is shadows, the rest is secret.
Writing On The Walls In South Africa
Chaim Even-Zohar writes about uncertainities over South Africa's diamond industry + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=26214
Diamond Road
Don't miss the documentary on diamonds on Discovery Times coming July 17.
More info @ http://times.discovery.com/tv-schedules/series.html?paid=141.14339.112572.29396.3
More info @ http://times.discovery.com/tv-schedules/series.html?paid=141.14339.112572.29396.3
Agate-staining In The Early Part Of The Century
(via The Journal of Gemmology, Vol.XIV, No.3, July 1974) M J O’Donoghue writes:
In 1913 Dr O Dreher published a book entitled Farben des Achates, in Idar Oberstein. Long out-of-print, there is no copy in the library of the Gemmological Association nor in the British Museum. However, in his recent book, Gemstone & Mineral Data Book, John Sinkankas summarizes a number of Dr Dreher’s findings.
For obtaining a red color Dr Dreher recommends a dye solution with the following composition: ¼ kg iron nails dissolved in 1 kg concentrated nitric acid. When the liquid is clear the agate slabs are soaked for a duration depending on their thickness, e.g. 3 mm thick, 6 – 10 days, 7 – 10 mm from 3 – 4 weeks. Stones are then heated in a closed crucible for 2 – 3 or 8 – 10 days again according to the original thickness. Dreher found the iron nitrate supplied by a chemical house less satisfactory than the somewhat cumbersome nail method. S. Hoffman worked through the same method to obtain red agate.
For blue Dreher used 250 g of yellow potassium ferrocyanide dissolved in 1 litre of lukewarm water. Stones were immersed for 8 – 14 days. They are then washed and subsequently placed in a lukewarm saturated solution of ferrous sulphate.
For black the stones are immersed in a solution composed of 375 g of sugar per litre in which they are soaked for 2 – 3 weeks, with the occasional addition of water to replace losses through evaporation. They are rinsed and dried and then placed in a bath of concentrated sulphuric acid. This is warmed for one hour until it is hot. The stones are soaked for 1 – 2 hours while the acid is brought close to boiling point (340ºC). They are carefully washed on removal. It was not necessary to bring the acid to boiling point to achieve carbonization of the sugar.
Green staining is accomplished by the use of a saturated solution of chromium trioxide in 1 litre of water. Immersion lasts from 8 – 14 days for thin slabs, 2 – 8 weeks for thickness of 3 – 10 mm. After removal and rinsing the agates are placed in ammonium carbamate acid carbonate followed by heating to redness.
In 1913 Dr O Dreher published a book entitled Farben des Achates, in Idar Oberstein. Long out-of-print, there is no copy in the library of the Gemmological Association nor in the British Museum. However, in his recent book, Gemstone & Mineral Data Book, John Sinkankas summarizes a number of Dr Dreher’s findings.
For obtaining a red color Dr Dreher recommends a dye solution with the following composition: ¼ kg iron nails dissolved in 1 kg concentrated nitric acid. When the liquid is clear the agate slabs are soaked for a duration depending on their thickness, e.g. 3 mm thick, 6 – 10 days, 7 – 10 mm from 3 – 4 weeks. Stones are then heated in a closed crucible for 2 – 3 or 8 – 10 days again according to the original thickness. Dreher found the iron nitrate supplied by a chemical house less satisfactory than the somewhat cumbersome nail method. S. Hoffman worked through the same method to obtain red agate.
For blue Dreher used 250 g of yellow potassium ferrocyanide dissolved in 1 litre of lukewarm water. Stones were immersed for 8 – 14 days. They are then washed and subsequently placed in a lukewarm saturated solution of ferrous sulphate.
For black the stones are immersed in a solution composed of 375 g of sugar per litre in which they are soaked for 2 – 3 weeks, with the occasional addition of water to replace losses through evaporation. They are rinsed and dried and then placed in a bath of concentrated sulphuric acid. This is warmed for one hour until it is hot. The stones are soaked for 1 – 2 hours while the acid is brought close to boiling point (340ºC). They are carefully washed on removal. It was not necessary to bring the acid to boiling point to achieve carbonization of the sugar.
Green staining is accomplished by the use of a saturated solution of chromium trioxide in 1 litre of water. Immersion lasts from 8 – 14 days for thin slabs, 2 – 8 weeks for thickness of 3 – 10 mm. After removal and rinsing the agates are placed in ammonium carbamate acid carbonate followed by heating to redness.
For Gemology Students
Prof Hermann Bank is one the most well known gemologist in the world. He shares the very lessons he had learnt during the past several decades as a teacher and researcher. All opportunities are accompanied by their own challenges. All the available knowledge in the world is accelerating at a phenomenal rate.
Prof Hermann Bank’s Address:
In his address, following the presentation of awards to the Gemmological Association of Great Britain at Goldsmith’s Hall on 14th November, 1983, including candidates from many different parts of the world, Prof Hermann Bank said:
Es war fur mich eine grosse Ehre, nach 7 Jahren wieder von der Gemmological Association of Great Britain eingeladen zu warden, um den erfolgreichen Kandidaten der Diplom-Prufugen des Jahres 1983 ihre Urkunden auszuhandigen. But as in 1976 I think that you would prefer that I try to continue in your language, and I beg you to excuse my poor English.
It was a great honor for me to be invited to present the awards of the Gemmological Association of Great Britain to the successful candidates of 1983, and I thank you very much for this invitation and the friendly welcome. The occasion is particularly pleasing for me for several reasons—(1) it is exactly 30 years since I passed the Diploma Examination in 1953 and became FGA; (2) as you have realized already, my eldest daughter is among you successful candidates; (3) it was pleasant to be able to present the Anderson-Bank Prize this year after Basic Anderson did it last year; (4) one must enjoy such an occasion anyhow. Since I have been asked to address you after having fulfilled my first task, I shall now try to fulfill my second too, and I should like especially to speak to the candidates.
You have now got your diplomas, and we hope that you do not think, as Goethe expressed in his Faust, ‘What you possess black on white you can confidently carry home,’ and relax on your success. It is one your duties to always perfect your gemological education, to keep your knowledge on a high standard, and you must allow me to give you some advice.
Gemology was much easier thirty years ago, and, if students of 1953 such a myself had remained on the level of knowledge of that time, they would now be lost. The developments and the progress have been so enormous in all fields of gemology that it has been necessary for us to learn steadily to keep always up to date.
There have been discovered new minerals. There have been found old minerals worth cutting. There have been invented new synthetic and artificial products. There have been effected new color manipulations, so many irradiations and diffusions and heatings, that it has also been necessary to use new techniques to disclose all these phenomena. Often the techniques must be more and more scientific to get the right results.
For a long time gemology was regarded only as a more commercial and technical appendix of mineralogy. The discovery of new mineral species by gemologists and the necessity of adoption of scientific methods to distinguish between gemstones and their substitutes or their manipulation have brought gemology to the level of a science. Last year the I M A (International Mineral Association) has formed its own commission on gem materials. That means, the I M A has accepted gemology on its own as scientific part of mineralogy. More and more mineralogists are taking an interest in gemological problems and assisting us to solve them, doing research on new minerals and varieties as well as on synthetic and imitation stones, their properties and distinguishing characteristics. Comprehensive information is increasingly important, and jeweler’s customers want more information. Therefore jewelers must have better education to be able to pass the required information on to their interested customers.
The Gemmological Association of Great Britain recognized this demand at the earliest stage and started gemological education courses over fifty years ago, and the courses have become an example and a model for gemological associations in other countries. The title FGA is highly esteemed throughout the world—hence the number of students every year. It is your proud duty to uphold the professional reputation which this title implies.
In the preliminary course the Gemmological Association of Great Britain tried to give the students a general idea, and, in the Diploma course, special theoretical knowledge and practical ability to use the various methods. However, we can only give and receive instruction until the day of the examination. Education combines the knowledge of the past with the unknown dark of the future by using wisely the present.
The candidates of today know—or at least should know—what we knew thirty years ago, and they also know what happened in these thirty years, but they and we do not know what problems will occur in the next thirty years. The unknown dark is spread over the developments of the future.
One fact is certain. New technologies will create new problems, and we can solve these problems only when we study steadily and try to keep on the newest stand of knowledge of the theoretical part and of the practical know-how of the methods.
A poet once said: ‘We must demand the extraordinary from ourselves to be able to do the ordinary.’
This we should at least try to do. If you have the slightest doubt, do not hesitate to consult an experienced colleague. We have a German proverb: ‘Was fur einen vielzuviel, ist fur 2 ein Kinderspiel.’ (What one cannot do is child’s play for two).
Experts are not made in heaven, and it is better to ask than to make an error. ‘Student is, who wants to learn something: Fellow or journey-man is, who knows something: Master is, who devised or invented something.’
Always take enough time to test a stone; never be in a hurry. Take your time also to study the Journal of Gemmology and other sources of information, and try to think, as Goethe expressed it: ‘Do not say, ‘Tomorrow I will do this and that: Do it, and wait until tomorrow and say then ‘I did it,’ which means, ‘Never put off till tomorrow what you can do today.’ Mineralogical gemologists and mineralogists try always to find and to develop new scientific equipments and methods which are suitable for easily distinguishing between gemstones and their substitutes, if possible without destroying them (neither gemstones nor substitutes).
Do not think that you only need to know a bit. A little learning is a dang’rous thing; Drink deep, or taste not the Pierian spring.’ (Pope: Essay on Criticism, 216). That means that we should try to obtain a thorough and comprehensive, broadly based knowledge.
The old Chinese said: ‘What you hear, you easily forget; What you see, you keep better in mind; Only what you have touched and worked with, you keep forever.’
So, please, use your instruments and get practice. In over ninety-nine percent of cases you can identify a stone by means of our classical gemological instruments—the polariscope, the conoscope, the refractometer, the microscope, the spectroscope, the UV lamp, etc. Only in very few cases is it necessary to consult X-ray powder methods or X-ray fluorescence or even X-ray topography or Tomography, the microprobe, IR spectroscopy or other more scientific equipments. But they are absolutely necessary for basic research and for doubtful cases.
It is not enough to have knowledge, it is necessary to use it.
And it is not enough to be willing, you must also do it.
So do work to get acquainted with methods and with all gemstones and their substitutes. The more you gain practice for yourself, the more you become sure on the one side but the more you also understand the verity of the two words of Socrates: ‘Scio nescio’ (I know what I do not know)
But Goethe consoles us when he writes: ‘It is not important what do know; but that we always have the right idea at the right moment.’
And it also is not correct that you should only buy instruments and textbooks, because often the purchase of a book is mistaken for the appropriation of the contents. So buy, use and read.
Successful candidates, I congratulate you on your Diplomas and I welcome you among the Fellows of the Gemmological Association of Great Britain. I wish you every success in your gemological future.
It is not important that one or the other of you will become a famous gemologist, but it is important that each and every one of you does his or her duty so that your clients have confidence in gemology and gemologists. To merit this confidence, do not remain on your present level of knowledge; study carefully to keep always up to date. Then I hope that your gemological practice will be characterized by a minimum of errors, a maximum of perfect results, and an optimum of joy. I wish you all the best and what is generally necessary in human life—a bit of good luck. Thank you.
Prof Hermann Bank’s Address:
In his address, following the presentation of awards to the Gemmological Association of Great Britain at Goldsmith’s Hall on 14th November, 1983, including candidates from many different parts of the world, Prof Hermann Bank said:
Es war fur mich eine grosse Ehre, nach 7 Jahren wieder von der Gemmological Association of Great Britain eingeladen zu warden, um den erfolgreichen Kandidaten der Diplom-Prufugen des Jahres 1983 ihre Urkunden auszuhandigen. But as in 1976 I think that you would prefer that I try to continue in your language, and I beg you to excuse my poor English.
It was a great honor for me to be invited to present the awards of the Gemmological Association of Great Britain to the successful candidates of 1983, and I thank you very much for this invitation and the friendly welcome. The occasion is particularly pleasing for me for several reasons—(1) it is exactly 30 years since I passed the Diploma Examination in 1953 and became FGA; (2) as you have realized already, my eldest daughter is among you successful candidates; (3) it was pleasant to be able to present the Anderson-Bank Prize this year after Basic Anderson did it last year; (4) one must enjoy such an occasion anyhow. Since I have been asked to address you after having fulfilled my first task, I shall now try to fulfill my second too, and I should like especially to speak to the candidates.
You have now got your diplomas, and we hope that you do not think, as Goethe expressed in his Faust, ‘What you possess black on white you can confidently carry home,’ and relax on your success. It is one your duties to always perfect your gemological education, to keep your knowledge on a high standard, and you must allow me to give you some advice.
Gemology was much easier thirty years ago, and, if students of 1953 such a myself had remained on the level of knowledge of that time, they would now be lost. The developments and the progress have been so enormous in all fields of gemology that it has been necessary for us to learn steadily to keep always up to date.
There have been discovered new minerals. There have been found old minerals worth cutting. There have been invented new synthetic and artificial products. There have been effected new color manipulations, so many irradiations and diffusions and heatings, that it has also been necessary to use new techniques to disclose all these phenomena. Often the techniques must be more and more scientific to get the right results.
For a long time gemology was regarded only as a more commercial and technical appendix of mineralogy. The discovery of new mineral species by gemologists and the necessity of adoption of scientific methods to distinguish between gemstones and their substitutes or their manipulation have brought gemology to the level of a science. Last year the I M A (International Mineral Association) has formed its own commission on gem materials. That means, the I M A has accepted gemology on its own as scientific part of mineralogy. More and more mineralogists are taking an interest in gemological problems and assisting us to solve them, doing research on new minerals and varieties as well as on synthetic and imitation stones, their properties and distinguishing characteristics. Comprehensive information is increasingly important, and jeweler’s customers want more information. Therefore jewelers must have better education to be able to pass the required information on to their interested customers.
The Gemmological Association of Great Britain recognized this demand at the earliest stage and started gemological education courses over fifty years ago, and the courses have become an example and a model for gemological associations in other countries. The title FGA is highly esteemed throughout the world—hence the number of students every year. It is your proud duty to uphold the professional reputation which this title implies.
In the preliminary course the Gemmological Association of Great Britain tried to give the students a general idea, and, in the Diploma course, special theoretical knowledge and practical ability to use the various methods. However, we can only give and receive instruction until the day of the examination. Education combines the knowledge of the past with the unknown dark of the future by using wisely the present.
The candidates of today know—or at least should know—what we knew thirty years ago, and they also know what happened in these thirty years, but they and we do not know what problems will occur in the next thirty years. The unknown dark is spread over the developments of the future.
One fact is certain. New technologies will create new problems, and we can solve these problems only when we study steadily and try to keep on the newest stand of knowledge of the theoretical part and of the practical know-how of the methods.
A poet once said: ‘We must demand the extraordinary from ourselves to be able to do the ordinary.’
This we should at least try to do. If you have the slightest doubt, do not hesitate to consult an experienced colleague. We have a German proverb: ‘Was fur einen vielzuviel, ist fur 2 ein Kinderspiel.’ (What one cannot do is child’s play for two).
Experts are not made in heaven, and it is better to ask than to make an error. ‘Student is, who wants to learn something: Fellow or journey-man is, who knows something: Master is, who devised or invented something.’
Always take enough time to test a stone; never be in a hurry. Take your time also to study the Journal of Gemmology and other sources of information, and try to think, as Goethe expressed it: ‘Do not say, ‘Tomorrow I will do this and that: Do it, and wait until tomorrow and say then ‘I did it,’ which means, ‘Never put off till tomorrow what you can do today.’ Mineralogical gemologists and mineralogists try always to find and to develop new scientific equipments and methods which are suitable for easily distinguishing between gemstones and their substitutes, if possible without destroying them (neither gemstones nor substitutes).
Do not think that you only need to know a bit. A little learning is a dang’rous thing; Drink deep, or taste not the Pierian spring.’ (Pope: Essay on Criticism, 216). That means that we should try to obtain a thorough and comprehensive, broadly based knowledge.
The old Chinese said: ‘What you hear, you easily forget; What you see, you keep better in mind; Only what you have touched and worked with, you keep forever.’
So, please, use your instruments and get practice. In over ninety-nine percent of cases you can identify a stone by means of our classical gemological instruments—the polariscope, the conoscope, the refractometer, the microscope, the spectroscope, the UV lamp, etc. Only in very few cases is it necessary to consult X-ray powder methods or X-ray fluorescence or even X-ray topography or Tomography, the microprobe, IR spectroscopy or other more scientific equipments. But they are absolutely necessary for basic research and for doubtful cases.
It is not enough to have knowledge, it is necessary to use it.
And it is not enough to be willing, you must also do it.
So do work to get acquainted with methods and with all gemstones and their substitutes. The more you gain practice for yourself, the more you become sure on the one side but the more you also understand the verity of the two words of Socrates: ‘Scio nescio’ (I know what I do not know)
But Goethe consoles us when he writes: ‘It is not important what do know; but that we always have the right idea at the right moment.’
And it also is not correct that you should only buy instruments and textbooks, because often the purchase of a book is mistaken for the appropriation of the contents. So buy, use and read.
Successful candidates, I congratulate you on your Diplomas and I welcome you among the Fellows of the Gemmological Association of Great Britain. I wish you every success in your gemological future.
It is not important that one or the other of you will become a famous gemologist, but it is important that each and every one of you does his or her duty so that your clients have confidence in gemology and gemologists. To merit this confidence, do not remain on your present level of knowledge; study carefully to keep always up to date. Then I hope that your gemological practice will be characterized by a minimum of errors, a maximum of perfect results, and an optimum of joy. I wish you all the best and what is generally necessary in human life—a bit of good luck. Thank you.
Cassiterite
Chemistry: Tin oxide (tin stone).
Crystal system: Tetragonal; prismatic, capped by pyramids; often twinned (geniculate); massive and granular, botryoidal, reniform with radial fibrous structure.
Color: Transparent to translucent; reddish brown to black, colorless, yellow.
Hardness: 6 - 7
Cleavage: Indistinct: brittle; Fracture: uneven, conchoidal.
Specific gravity: 6.8 – 7.1
Refractive index: 1.997 – 2.093; Uniaxial positive; 0.096.
Luster: Vitreous to adamantine; greasy on fracture.
Dispersion: Very high.
Dichroism: Weak to moderate; yellowish, brownish.
Occurrence: Granite and alluvial, high temperature hydrothermal veins and pegmatites; Australia, Bolivia, Malaysia, Mexico, Namibia, England.
Notes:
Principal ore of Tin; collectors stone; may be confused with diamond, hematite, sphene, zircon; faceted and cabochons.
Crystal system: Tetragonal; prismatic, capped by pyramids; often twinned (geniculate); massive and granular, botryoidal, reniform with radial fibrous structure.
Color: Transparent to translucent; reddish brown to black, colorless, yellow.
Hardness: 6 - 7
Cleavage: Indistinct: brittle; Fracture: uneven, conchoidal.
Specific gravity: 6.8 – 7.1
Refractive index: 1.997 – 2.093; Uniaxial positive; 0.096.
Luster: Vitreous to adamantine; greasy on fracture.
Dispersion: Very high.
Dichroism: Weak to moderate; yellowish, brownish.
Occurrence: Granite and alluvial, high temperature hydrothermal veins and pegmatites; Australia, Bolivia, Malaysia, Mexico, Namibia, England.
Notes:
Principal ore of Tin; collectors stone; may be confused with diamond, hematite, sphene, zircon; faceted and cabochons.
Monday, July 09, 2007
Anything Else
Memorable quote (s) from the movie:
David Dobel (Woody Allen): Since the beginning of time people have been, you know, frightened and, and unhappy, and they're scared of death, and they're scared of getting old, and there's always been priests around, and shamans, and now shrinks, to tell 'em, "Look, I know you're frightened, but I can help you. Of course, it is going to cost you a few bucks...” But they can't help you, Falk, because life is what it is.
David Dobel (Woody Allen): Since the beginning of time people have been, you know, frightened and, and unhappy, and they're scared of death, and they're scared of getting old, and there's always been priests around, and shamans, and now shrinks, to tell 'em, "Look, I know you're frightened, but I can help you. Of course, it is going to cost you a few bucks...” But they can't help you, Falk, because life is what it is.
Brazilianite
Chemistry: Hydrous sodium aluminum phosphate.
Crystal system: Monoclinic; short prism; large spear-shaped.
Color: Transparent to translucent; colorless with striations; yellow/green, yellow, colorless (rare).
Hardness: 5.5
Cleavage: Perfect: 1 direction, parallel to pinacoid faces; Fracture: brittle, conchoidal.
Specific gravity: 2.98
Refractive index: 1.603 – 1.623; 0.02
Luster: Vitreous.
Dispersion: Low.
Dichroism: Weak (merely a change in shade).
Occurrence: Hydrothermal in pegmatite cavities. Brazil, U.S.A.
Notes
Collector's stone; heat sensitive; first found in 1944; may look like beryl, chrysoberyl, topaz, but R.I and DR different.
Crystal system: Monoclinic; short prism; large spear-shaped.
Color: Transparent to translucent; colorless with striations; yellow/green, yellow, colorless (rare).
Hardness: 5.5
Cleavage: Perfect: 1 direction, parallel to pinacoid faces; Fracture: brittle, conchoidal.
Specific gravity: 2.98
Refractive index: 1.603 – 1.623; 0.02
Luster: Vitreous.
Dispersion: Low.
Dichroism: Weak (merely a change in shade).
Occurrence: Hydrothermal in pegmatite cavities. Brazil, U.S.A.
Notes
Collector's stone; heat sensitive; first found in 1944; may look like beryl, chrysoberyl, topaz, but R.I and DR different.
Brazilianite
Chemistry: Hydrous sodium aluminum phosphate.
Crystal system: Monoclinic; short prism; large spear-shaped.
Color: Transparent to translucent; colorless with striations; yellow/green, yellow, colorless (rare).
Hardness: 5.5
Cleavage: Perfect: 1 direction, parallel to pinacoid faces; Fracture: brittle, conchoidal.
Specific gravity: 2.98
Refractive index: 1.603 – 1.623; 0.02
Luster: Vitreous.
Dispersion: Low.
Dichroism: Weak (merely a change in shade).
Occurrence: Hydrothermal in pegmatite cavities. Brazil, U.S.A.
Notes
Collector's stone; heat sensitive; first found in 1944; may look like beryl, chrysoberyl, topaz, but R.I and DR different.
Crystal system: Monoclinic; short prism; large spear-shaped.
Color: Transparent to translucent; colorless with striations; yellow/green, yellow, colorless (rare).
Hardness: 5.5
Cleavage: Perfect: 1 direction, parallel to pinacoid faces; Fracture: brittle, conchoidal.
Specific gravity: 2.98
Refractive index: 1.603 – 1.623; 0.02
Luster: Vitreous.
Dispersion: Low.
Dichroism: Weak (merely a change in shade).
Occurrence: Hydrothermal in pegmatite cavities. Brazil, U.S.A.
Notes
Collector's stone; heat sensitive; first found in 1944; may look like beryl, chrysoberyl, topaz, but R.I and DR different.
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