The Gem & Jewellery Export Promotion Council of India will be hosting the first Indo-US Jewelry Business Development Conference for jewelry retailers on October 1-5 at Mumbai's Marriott Renaissance.
Top U.S and Canadian senior business development executives and directors of merchandise are invited to attend the all-expense paid, jewelry business development event. The event is being organized by GJEPC, and R&B Partners, LLP, a Stamford, Conn.-based branding, marketing, and special event consulting firm.
Friday, May 18, 2007
A Question Of Origin: A Different View
(via Gemological Digest, Vol.3, No.1, 1990) Grahame Brown writes:
Your well documented arguments against using origin reports to support price premiums for selected colored stones, should stimulate gemologists to think this very real problem through, rather than dismissing your arguments as being commercially unrealistic, or worse still, acquiescing to the rather dubiously based status quo.
Personally, I fully support the general thrust of your arguments, and wish to raise several additional points for consideration.
1. Researchers, species collectors and investors, excepted, why do human beings purchase colored stones? Surely the major factor influencing the desirability and subsequent purchase of a colored stone must be those visual characteristics contributing to the particular gem’s beauty and rarity. It is a fact that geography has little proven influence over the appearance of a colored stone.
2. Why should the presence of any visually detectable inclusion (s) in a colored stone not logically degrade, rather than sometimes upgrade, the value of the stone? Clarity should be a significant determinant of value; the country of origin of the gemstone’s inclusion should not practically influence its global value.
3. If origin reports are of such significance to the value of colored stones, why are these not routinely prepared for all colored stones?
4. If the gemologist wishes, or is forced by perceived necessity, to issue an origin report for a particular colored stone, then what data does he or she have to support their assignment of origin to that colored stone? The factual answer to this question is……precious little. Certainly, several most useful photoatlases of gemstone inclusions have been published, but none of these present an exhaustive review of characteristic inclusions found in colored stones from all past or present mines. This comparative information is essential if the origin of a colored stone is to be determined with any degree of accuracy. Yes, systematic collections of colored stones do exist, e.g. the GIA’s reference collection, but this collection is not readily accessible to an antipodean gemologist, who may be attempting to determine the origin of a troublesome colored stone. Excellent though the GIA reference collection is….is still incomplete. Perhaps the most striking inadequacy of gemology’s knowledge of characteristic gemstone inclusions is the fact that less than 50 per cent (author’s estimate) of the world’s colored stone deposits have been described, in any way, in the gemological literature. Simply put, insufficient data exists to allow error-free origin reports to be issued by the majority of gemologists.
Origin reports for colored stones may be economic necessity for some gemologists, but to me (for the reasons expressed above) they mostly represent quasi-scientific gemological humbug.
Your well documented arguments against using origin reports to support price premiums for selected colored stones, should stimulate gemologists to think this very real problem through, rather than dismissing your arguments as being commercially unrealistic, or worse still, acquiescing to the rather dubiously based status quo.
Personally, I fully support the general thrust of your arguments, and wish to raise several additional points for consideration.
1. Researchers, species collectors and investors, excepted, why do human beings purchase colored stones? Surely the major factor influencing the desirability and subsequent purchase of a colored stone must be those visual characteristics contributing to the particular gem’s beauty and rarity. It is a fact that geography has little proven influence over the appearance of a colored stone.
2. Why should the presence of any visually detectable inclusion (s) in a colored stone not logically degrade, rather than sometimes upgrade, the value of the stone? Clarity should be a significant determinant of value; the country of origin of the gemstone’s inclusion should not practically influence its global value.
3. If origin reports are of such significance to the value of colored stones, why are these not routinely prepared for all colored stones?
4. If the gemologist wishes, or is forced by perceived necessity, to issue an origin report for a particular colored stone, then what data does he or she have to support their assignment of origin to that colored stone? The factual answer to this question is……precious little. Certainly, several most useful photoatlases of gemstone inclusions have been published, but none of these present an exhaustive review of characteristic inclusions found in colored stones from all past or present mines. This comparative information is essential if the origin of a colored stone is to be determined with any degree of accuracy. Yes, systematic collections of colored stones do exist, e.g. the GIA’s reference collection, but this collection is not readily accessible to an antipodean gemologist, who may be attempting to determine the origin of a troublesome colored stone. Excellent though the GIA reference collection is….is still incomplete. Perhaps the most striking inadequacy of gemology’s knowledge of characteristic gemstone inclusions is the fact that less than 50 per cent (author’s estimate) of the world’s colored stone deposits have been described, in any way, in the gemological literature. Simply put, insufficient data exists to allow error-free origin reports to be issued by the majority of gemologists.
Origin reports for colored stones may be economic necessity for some gemologists, but to me (for the reasons expressed above) they mostly represent quasi-scientific gemological humbug.
Thursday, May 17, 2007
Colorado Rhodochrosite
The Sweet Home mine in Colarado's Alma mining district has been known since 1872 for silver, but more recently the mine has become famous for producing top quality rhodochrosite crystals. The best qualities are well-formed, translucent to transparent rhombohedrons with intense orange red color. The colors are stunning red like some of the top quality rubies.
Rhodochrosite is soft and has perfect cleavage in three directions so faceting the stone is difficult. The cut yield can range between 5% and 20% depending on the size and shape of the rough and the experience of the cutter. The smaller sizes may be calibrated in 0.5mm increments as oval, round, princess, cushion, emerald and trilliants. Cabochons both calibrated and free sizes can also be polished based on the quality of the rough. Cabochons displaying chatoyancy with four rayed stars have also been found. It is believed that most faceted stones are untreated, while some of the cabochons may be stabilized during the cutting process.
The cut rhodochrosite is being sold by Mr Van Wagoner, Beija-flor Gems, Haiku, Hawaii. They expect the stocks to last for two or three years, after which few stones will be available in the market.
Rhodochrosite is soft and has perfect cleavage in three directions so faceting the stone is difficult. The cut yield can range between 5% and 20% depending on the size and shape of the rough and the experience of the cutter. The smaller sizes may be calibrated in 0.5mm increments as oval, round, princess, cushion, emerald and trilliants. Cabochons both calibrated and free sizes can also be polished based on the quality of the rough. Cabochons displaying chatoyancy with four rayed stars have also been found. It is believed that most faceted stones are untreated, while some of the cabochons may be stabilized during the cutting process.
The cut rhodochrosite is being sold by Mr Van Wagoner, Beija-flor Gems, Haiku, Hawaii. They expect the stocks to last for two or three years, after which few stones will be available in the market.
Australia’s Quota System For Cultured Pearls
I wish the colored stone industry had similar quota systems to protect natural environment + long term sustainability plan.
(via Arafura Pearls Holdings Ltd (2006) Prospectus/ The Australian Gemmologist, 2007, Vol.23, No.2, April-June 2007) Australian Gemmologist writes:
Unlike the rest of the world, the Australian pearl culturing industry is highly regulated through the use of a government controlled ‘oyster’ quota system. Each producer must hold a pearl license from the relevant state government body. Presently quotas are set for both wild and hatchery bred Pinctada maxima.
This quota system limits the number of shell that can be seeded and can be put into cultivation each licensing year. The sole purpose of this rigidly enforced quota system is to protect naturally occurring stocks of P. maxima, allow their natural regeneration, and so maintain the long term sustainability of the Australian South Sea pearl industry and its markets.
Presently the annual quota of shell for all licensed produces is 1,432,000 shell of specified size (120mm minimum diameter).
Wild oyster quota: 572,000 (WA); 120,000 (NT); Total: 692,000
Hatchery quota: 350,000 (WA); 300,000 (NT); Total: 650,000
Total oyster quota: 922,000 (WA); 420,000 (NT); Total: 1.342,000
The oyster quotas in the Northern Territory and Western Australia are closely held by a small number of producers. The three largest quota holders in Australia are the Paspaley Group, the Kailis Group, and Arafura Pearls who have access to approximately 75% of the available quota either directly or indirectly. The remaining quota is spread amongst several other pearl farmers.
An independent review of the Western Australian Pearling Act 1990 was completed in 2000 within the framework of the National Competition Policy. This review confirmed that the existing regulations and restrictions associated with wild stock oysters were justified. The State and Territory governments are currently completing a five year review of their hatchery policies to determine any update in hatchery quota regulation.
Pearling is Australia’s second largest aquacultural activity by gross value of production. Subject to currency and price movements, the Australian cultured pearl industry produces approximately $A180 - $220 million pearls in wholesale value each year; of which Western Australia contributes approximately 80% and the Northern Territory 20%, Queensland production is minimal. By volume, Australia produces approximately 2.5 – 3 tonnes of South Sea Pearls per annum.
(via Arafura Pearls Holdings Ltd (2006) Prospectus/ The Australian Gemmologist, 2007, Vol.23, No.2, April-June 2007) Australian Gemmologist writes:
Unlike the rest of the world, the Australian pearl culturing industry is highly regulated through the use of a government controlled ‘oyster’ quota system. Each producer must hold a pearl license from the relevant state government body. Presently quotas are set for both wild and hatchery bred Pinctada maxima.
This quota system limits the number of shell that can be seeded and can be put into cultivation each licensing year. The sole purpose of this rigidly enforced quota system is to protect naturally occurring stocks of P. maxima, allow their natural regeneration, and so maintain the long term sustainability of the Australian South Sea pearl industry and its markets.
Presently the annual quota of shell for all licensed produces is 1,432,000 shell of specified size (120mm minimum diameter).
Wild oyster quota: 572,000 (WA); 120,000 (NT); Total: 692,000
Hatchery quota: 350,000 (WA); 300,000 (NT); Total: 650,000
Total oyster quota: 922,000 (WA); 420,000 (NT); Total: 1.342,000
The oyster quotas in the Northern Territory and Western Australia are closely held by a small number of producers. The three largest quota holders in Australia are the Paspaley Group, the Kailis Group, and Arafura Pearls who have access to approximately 75% of the available quota either directly or indirectly. The remaining quota is spread amongst several other pearl farmers.
An independent review of the Western Australian Pearling Act 1990 was completed in 2000 within the framework of the National Competition Policy. This review confirmed that the existing regulations and restrictions associated with wild stock oysters were justified. The State and Territory governments are currently completing a five year review of their hatchery policies to determine any update in hatchery quota regulation.
Pearling is Australia’s second largest aquacultural activity by gross value of production. Subject to currency and price movements, the Australian cultured pearl industry produces approximately $A180 - $220 million pearls in wholesale value each year; of which Western Australia contributes approximately 80% and the Northern Territory 20%, Queensland production is minimal. By volume, Australia produces approximately 2.5 – 3 tonnes of South Sea Pearls per annum.
A Question Of Origin
2007: I think John Koivula was right. The laboratories have no need for origin, and in some cases there is no way of knowing where the stones came from.
(via Gemological Digest, Vol.3, No.1, 1990) John Koivula writes:
With regard to your article, “A Question of Origin,” I agree with your basic premise that where determining country of origin in a gem is concerned, there is some truth in the saying ignorance is bliss. The more knowledge one gains on this subject, the more complex the problem of geographical origin becomes. While an experienced, knowledgeable inclusion expert can identify country of origin for some stones, in most cases it is impossible to determine the precise country of origin. The inclusion identification work that is done by a few colleagues and myself at GIA is done as a scientific endeavor to expand our knowledge of gems—not to prepare country of origin reports.
Your statement that ‘consumer could then be told honestly that these (origin reports) are intended for collectors and researchers’ is part incorrect, because most researchers have no need for origin reports of the type produced by the various gemological laboratories that issue them. Most inclusion researchers study the stones themselves and draw information from the various professional gemological and other earth science publications. In the 25 years that I have done research in this field, I have never found a need for an origin report.
With regard to your comments on there being more than one sapphire mining area in the State of Montana, please be assured that when Dr Gubelin and I discuss inclusions in sapphires from Yogo Gulch in the Photoatlas, we are most definitely referring to stones from that specific locality. Also, in your discussion of Kashmir sapphires you state: “Since the mine is (and has been for many years) off-limits to foreigners, the question arises as to where gemologists got the study samples.” You fail to mention or reference, however, a relatively recent major article on the Kashmir deposit in which the authors obtained their information and samples first-hand at the mining area (D. Atkinson and R. Kothawala, “Kashmir Sapphire,” Gems & Gemology, Vol.19, No.2, 1983, pp 64-76). For some interested in scientific research on Kashmir sapphires, a 1983 article would seem to be at least as valuable as one published in 1890—especially considering the technological advances that have occurred in the interim. I am sure the gemological community is also looking forward to the results of your research on the 1 kg (5000 carats) of known Kashmir sapphire rough you had the good fortune to obtain.
(via Gemological Digest, Vol.3, No.1, 1990) John Koivula writes:
With regard to your article, “A Question of Origin,” I agree with your basic premise that where determining country of origin in a gem is concerned, there is some truth in the saying ignorance is bliss. The more knowledge one gains on this subject, the more complex the problem of geographical origin becomes. While an experienced, knowledgeable inclusion expert can identify country of origin for some stones, in most cases it is impossible to determine the precise country of origin. The inclusion identification work that is done by a few colleagues and myself at GIA is done as a scientific endeavor to expand our knowledge of gems—not to prepare country of origin reports.
Your statement that ‘consumer could then be told honestly that these (origin reports) are intended for collectors and researchers’ is part incorrect, because most researchers have no need for origin reports of the type produced by the various gemological laboratories that issue them. Most inclusion researchers study the stones themselves and draw information from the various professional gemological and other earth science publications. In the 25 years that I have done research in this field, I have never found a need for an origin report.
With regard to your comments on there being more than one sapphire mining area in the State of Montana, please be assured that when Dr Gubelin and I discuss inclusions in sapphires from Yogo Gulch in the Photoatlas, we are most definitely referring to stones from that specific locality. Also, in your discussion of Kashmir sapphires you state: “Since the mine is (and has been for many years) off-limits to foreigners, the question arises as to where gemologists got the study samples.” You fail to mention or reference, however, a relatively recent major article on the Kashmir deposit in which the authors obtained their information and samples first-hand at the mining area (D. Atkinson and R. Kothawala, “Kashmir Sapphire,” Gems & Gemology, Vol.19, No.2, 1983, pp 64-76). For some interested in scientific research on Kashmir sapphires, a 1983 article would seem to be at least as valuable as one published in 1890—especially considering the technological advances that have occurred in the interim. I am sure the gemological community is also looking forward to the results of your research on the 1 kg (5000 carats) of known Kashmir sapphire rough you had the good fortune to obtain.
Inclusions As Criteria In Gemstone Origin Reports
2007: The amazing thing is despite the limitations, the trade still insists for origin certification and a few gem testing laboratories are more than happy to provide their services at a cost.
(via Gemological Digest, No.3, No.1, 1990) Edwin Roedder writes:
Richard W Hughes has asked for my comments on the question of the use of gemstone origin reports and in particular on his paper on that subject in this same issue. As a mineralogist-geochemist who has only seen the fringes of the field of gemology over the years, it is not appropriate for me to discuss the uses being made of origin reports in the gem trade. I can only say that Mr Hughes paper seems to present a very coherent, well-documented and cogent review of the subject. Although I have read many scientific papers dealing with the inclusions in gems and the possibility of their use in determining origin, I have never seen an actual origin report, and hence my only comments deal the validity of the inclusions criteria that might be used in issuing any such report. These comments are quite apart from the difficulties mentioned by Mr Hughes of obtaining material of verifiable origin on which to establish such criteria.
I will discuss two aspects: first, the effects of the inherent variation in the inclusion population in samples from a given locality, and second, the general similarity of the inclusion populations in samples from many different localities.
Variation of the inclusion parameters within samples from a given locality
Many different kinds of inclusions, both fluid and solid, can be trapped in a given mineral from a given locality. The reasons for this wide range lie in the basic nature of the origin of inclusions. Primary inclusions formed during the growth of the host crystal, can trap any solid, liquid, or vapor phases that happen to be present at the time of growth. The much more common secondary inclusions are trapped as a result of healing of fractures in the host crystal that form at some later time; this later time may be immediately after completion of the growth of the host crystal, or as much as billions of years later.
Although I have studied a number of gem minerals, the bulk of my inclusion work has been on non-gem materials, but I am certain that the principals involved in the two types of materials are identical; the only real difference is in the rarity of gem minerals, and in the necessarily low abundance of inclusions in high quality stones. When I study the inclusions in many samples of a given mineral from a given locality (personally collected so there is no ambiguity as to sample origin), I usually find a large range in inclusion types, habits, and compositions in the different samples. The primary solid inclusions represent the trapping of those other solid phases that just happened to be present at the time of growth and which were enclosed rather than pushed aside by the growing crystal. If different solid phases were present in different part of the deposit, the solid inclusions that are trapped will differ similarly. Even the fluid that is trapped in primary inclusions can show gross differences in composition between the core and rim of a single host crystal, if the conditions have changed during that growth. Since some of the larger crystals in metamorphic rocks have recently been shown to have grown at rates in the range of only a millimeter in a million years, it would not be surprising to find that the composition of the fluids bathing the crystal had changed during its growth.
Secondary fluid inclusions (i.e most of the inclusions making up the feathers, etc in gems), represent one or more periods of fracturing and rehealing of the host crystal. It is very common to find that such fracturing has occurred at several different times, perhaps millions of years apart, and in the presence of very different fluids. So two different feathers in a single crystal may contain very different fluids.
Since such wide variations in the inclusions in different crystal or parts of a crystal from a single locality are so common, it may be difficult or even impossible to set up inclusion criteria that would permit a valid origin report to be written for a single sample of the host mineral from that locality. Various specific inclusion parameters seen in the single sample may match features seen commonly in other crystals from that same locality, but the wide range of possible parameter values, and the all-too-common atypical inclusions diminish the degree of confidence in any assignment of the sample to that locality. Although my work involves learning about the inclusions in samples from known localities, I would find it exceedingly difficult to have to work in reverse, as the gemologist must, and identify the locality of origin by the study of inclusions in a given sample. If presented with a single sample from one of the many localities I have studied, I might be able to venture an educated guess as to one (or more, as detailed below) possible localities, and in most cases I could say with some confidence that certain other localities were impossible, but I could not go beyond that. Perhaps in the future, when far more inclusion parameters can be determined with increased precision, this basic uncertainity might be reduced. Thus non-destructive chemical (and isotopic) analyses of the minor and trace elements in the fluids of inclusions might provide fingerprints that will greatly reduce the ambiguity in the assignment of origin, but will never eliminate.
Similarity of inclusion populations in samples from different localities
Gemstones, just as other natural crystals, have crystallized in a variety of geological environments, but even so, there is a relatively limited range for any given gem. Thus most gem quality corundums have formed in only a very few limited types of environment, such as certain slowly cooled igneous and metamorphic rocks. As a result, the overall range in composition of their inclusions, both solid and liquid is limited. A relatively rare phase as a solid inclusion may be a valuable but not necessarily unique indicator, e.g. the uranium pyrochlore referred to in Pailin sapphires. But many solid inclusions are of common minerals that might be expected in many localities, particularly in localities that are already similar geologically in virtue of the fact that a given gemstone is found in each. (On the other hand, certain solid inclusions can effectively exclude specific geologic environments. Thus fine fibrous amphibole inclusions are not expected in stones from a magmatic or high temperature metamorphic environment.)
Similarly, liquid inclusions in most minerals normally contain water + salt + CO2 major components. The amounts of the latter two may vary widely. For many years it was generally accepted that emeralds containing highly saline inclusions (i.e a saturated water solution plus a daughter crystal of NaCl) came from Colombian emeralds, but since then similar inclusions have been described in emeralds from other localities. CO2 is a major component in the fluid inclusions in many rock types that bear gem corundum and hence is not definitive of any specific locality.
If all the above caveats seem unduly pessimistic a to the significance of origin reports, please note that I have described only one of the many parameters that may be involved in judging the origin of a stone; I am not qualified to discuss color and its distribution and possible modification, fluorescence, density, refractive index, etc.
In closing, let me add one additional caveat. Origin reports must distinguish between synthetic and natural stones, as this is far greater importance in commerce than the difference between different localities, large as these are. In the past, the inclusions in gems have provided reliable criteria for differentiating. Synthetic stones generally had types of inclusions that were uncharacteristic of those from nature, and did not contain those that were characteristic of the natural stones. These differences are caused by the use of entirely different growth processes and conditions in the laboratory than were used in nature. Thus the manufacture of large corundum crystals in various colors by flame fusion provides high quality material for pennies per carat.
But it should be noted that the huge differences in value compared with natural stones provides a great incentive to eliminate these recognizable differences in the final product. Once careful study shows the nature of the inclusions present in (and believed to be characteristic of) the natural stones, it is highly likely that attempts will be made to grow synthetic stones by processes such that the inclusions will also appear natural. Presently available laboratory equipment can duplicate the pressure, temperature, and chemical environment under which any gem has formed in nature. This has been done with emeralds, which have been grown synthetically with strongly saline inclusions, and I have no reason to doubt that other natural appearing gems will be similarly produced and sold, if they have not been already.
(via Gemological Digest, No.3, No.1, 1990) Edwin Roedder writes:
Richard W Hughes has asked for my comments on the question of the use of gemstone origin reports and in particular on his paper on that subject in this same issue. As a mineralogist-geochemist who has only seen the fringes of the field of gemology over the years, it is not appropriate for me to discuss the uses being made of origin reports in the gem trade. I can only say that Mr Hughes paper seems to present a very coherent, well-documented and cogent review of the subject. Although I have read many scientific papers dealing with the inclusions in gems and the possibility of their use in determining origin, I have never seen an actual origin report, and hence my only comments deal the validity of the inclusions criteria that might be used in issuing any such report. These comments are quite apart from the difficulties mentioned by Mr Hughes of obtaining material of verifiable origin on which to establish such criteria.
I will discuss two aspects: first, the effects of the inherent variation in the inclusion population in samples from a given locality, and second, the general similarity of the inclusion populations in samples from many different localities.
Variation of the inclusion parameters within samples from a given locality
Many different kinds of inclusions, both fluid and solid, can be trapped in a given mineral from a given locality. The reasons for this wide range lie in the basic nature of the origin of inclusions. Primary inclusions formed during the growth of the host crystal, can trap any solid, liquid, or vapor phases that happen to be present at the time of growth. The much more common secondary inclusions are trapped as a result of healing of fractures in the host crystal that form at some later time; this later time may be immediately after completion of the growth of the host crystal, or as much as billions of years later.
Although I have studied a number of gem minerals, the bulk of my inclusion work has been on non-gem materials, but I am certain that the principals involved in the two types of materials are identical; the only real difference is in the rarity of gem minerals, and in the necessarily low abundance of inclusions in high quality stones. When I study the inclusions in many samples of a given mineral from a given locality (personally collected so there is no ambiguity as to sample origin), I usually find a large range in inclusion types, habits, and compositions in the different samples. The primary solid inclusions represent the trapping of those other solid phases that just happened to be present at the time of growth and which were enclosed rather than pushed aside by the growing crystal. If different solid phases were present in different part of the deposit, the solid inclusions that are trapped will differ similarly. Even the fluid that is trapped in primary inclusions can show gross differences in composition between the core and rim of a single host crystal, if the conditions have changed during that growth. Since some of the larger crystals in metamorphic rocks have recently been shown to have grown at rates in the range of only a millimeter in a million years, it would not be surprising to find that the composition of the fluids bathing the crystal had changed during its growth.
Secondary fluid inclusions (i.e most of the inclusions making up the feathers, etc in gems), represent one or more periods of fracturing and rehealing of the host crystal. It is very common to find that such fracturing has occurred at several different times, perhaps millions of years apart, and in the presence of very different fluids. So two different feathers in a single crystal may contain very different fluids.
Since such wide variations in the inclusions in different crystal or parts of a crystal from a single locality are so common, it may be difficult or even impossible to set up inclusion criteria that would permit a valid origin report to be written for a single sample of the host mineral from that locality. Various specific inclusion parameters seen in the single sample may match features seen commonly in other crystals from that same locality, but the wide range of possible parameter values, and the all-too-common atypical inclusions diminish the degree of confidence in any assignment of the sample to that locality. Although my work involves learning about the inclusions in samples from known localities, I would find it exceedingly difficult to have to work in reverse, as the gemologist must, and identify the locality of origin by the study of inclusions in a given sample. If presented with a single sample from one of the many localities I have studied, I might be able to venture an educated guess as to one (or more, as detailed below) possible localities, and in most cases I could say with some confidence that certain other localities were impossible, but I could not go beyond that. Perhaps in the future, when far more inclusion parameters can be determined with increased precision, this basic uncertainity might be reduced. Thus non-destructive chemical (and isotopic) analyses of the minor and trace elements in the fluids of inclusions might provide fingerprints that will greatly reduce the ambiguity in the assignment of origin, but will never eliminate.
Similarity of inclusion populations in samples from different localities
Gemstones, just as other natural crystals, have crystallized in a variety of geological environments, but even so, there is a relatively limited range for any given gem. Thus most gem quality corundums have formed in only a very few limited types of environment, such as certain slowly cooled igneous and metamorphic rocks. As a result, the overall range in composition of their inclusions, both solid and liquid is limited. A relatively rare phase as a solid inclusion may be a valuable but not necessarily unique indicator, e.g. the uranium pyrochlore referred to in Pailin sapphires. But many solid inclusions are of common minerals that might be expected in many localities, particularly in localities that are already similar geologically in virtue of the fact that a given gemstone is found in each. (On the other hand, certain solid inclusions can effectively exclude specific geologic environments. Thus fine fibrous amphibole inclusions are not expected in stones from a magmatic or high temperature metamorphic environment.)
Similarly, liquid inclusions in most minerals normally contain water + salt + CO2 major components. The amounts of the latter two may vary widely. For many years it was generally accepted that emeralds containing highly saline inclusions (i.e a saturated water solution plus a daughter crystal of NaCl) came from Colombian emeralds, but since then similar inclusions have been described in emeralds from other localities. CO2 is a major component in the fluid inclusions in many rock types that bear gem corundum and hence is not definitive of any specific locality.
If all the above caveats seem unduly pessimistic a to the significance of origin reports, please note that I have described only one of the many parameters that may be involved in judging the origin of a stone; I am not qualified to discuss color and its distribution and possible modification, fluorescence, density, refractive index, etc.
In closing, let me add one additional caveat. Origin reports must distinguish between synthetic and natural stones, as this is far greater importance in commerce than the difference between different localities, large as these are. In the past, the inclusions in gems have provided reliable criteria for differentiating. Synthetic stones generally had types of inclusions that were uncharacteristic of those from nature, and did not contain those that were characteristic of the natural stones. These differences are caused by the use of entirely different growth processes and conditions in the laboratory than were used in nature. Thus the manufacture of large corundum crystals in various colors by flame fusion provides high quality material for pennies per carat.
But it should be noted that the huge differences in value compared with natural stones provides a great incentive to eliminate these recognizable differences in the final product. Once careful study shows the nature of the inclusions present in (and believed to be characteristic of) the natural stones, it is highly likely that attempts will be made to grow synthetic stones by processes such that the inclusions will also appear natural. Presently available laboratory equipment can duplicate the pressure, temperature, and chemical environment under which any gem has formed in nature. This has been done with emeralds, which have been grown synthetically with strongly saline inclusions, and I have no reason to doubt that other natural appearing gems will be similarly produced and sold, if they have not been already.
Wednesday, May 16, 2007
Opal From Piaui, Brazil
Piaui State (Brazil) is well-known to produce a variety of opals. Some rough and cut play of color opals are of high quality; cat's eye specimens are also available. Pedro II (or Pedro Segundo) is an important locality for play of color opals in the state. There are many new operational mines in the area. More opal production is anticipated as additional mines are reworked in part due to State government's assistance in promoting awareness of Piaui's opals.
East And West: The Ancient Gem Trade Between India and Rome
2007: Here is a fascinating story on gem trade and practices of the ancient world. Even today the concept remains pretty much the same; instead we use new jargons. It's educational and entertaining.
(via Gemological Digest, Vol.3, No.1, 1990) Peter Francis, Jr writes:
Abstract
The Roman Empire was among the best customers of the ancient world. From outside the Empire she sought items of luxury, especially precious gems. India was pleased to supply the insatiable appetite of the Roman elite. In turn, Rome paid mostly in gold coin, and supplied India with only one desired luxury, coral. The ancient gem trade was characterized by much mystery surrounding the sources of jewels, at least some of it purposeful smoke screen to ward off competition. In addition, there was general ignorance about the nature of gems such as pearls and coral. Even more important than the commerce in what we call precious stones was that in semi precious stones. Recent archaeological work has helped reveal some of the facts of this once thriving Indian industry.
Introduction
To the ancient Romans, the East, especially India, was the depository of all wealth. The Indians not only sold her mineral treasures to Rome, but were leaders in developing technologies that allowed them to be exploited.
Just over 2000 years ago the sea-faring Arabs taught Roman sailors an important secret: how to sail through the Erythraean or Red Sea, which then included the whole of the western Indian Ocean. The secret involved understanding the predominant wind patters by which ships could sail from west to east for a few months and then back from east to west during the other half of the year. This took advantage of the famous trade winds.
In those days Rome was the greatest power in the West. Aristrocrats were only politically ascendant, but also fabulously wealthy. They demanded objects that could prove their wealth beyond doubt, especially those for ostentatious display. For a very long time the best way to show off wealth has been to wear jewelry. Precious stones set in precious metals and worn by the precious few are a principal means of demonstrating that one has arrived and is rich, whether nouveau or otherwise.
This is why the discovery of a simple sea route to the East was so important to the Romans. Above all, the East meant wealth, treasure, gems and jewels beyond imagination; it was considered the depository of all valuable goods.
There were two mighty empires in the East: China and India. China was a wealthy land but also an impenetrable mystery. Though trade trickled across mountains and deserts between China and Rome, sea routes were long and dangerous and hardly ever used over such a vast distance. The Mediterranean world and China were isolated for centuries, save for the Silk Route, which was periodically closed by Central Asian bandits whenever control was weak in the Middle Kingdom.
But India was different story. A land widely renowned for its treasure, India had long traded luxury products to the western world. Millenia before Rome was built, carnelian and lapis lazuli were sold by the Indus Valley Civilization to the city states of Mesopotamia. King Solomon of Israel around 1000 B.C sent ships to Ophir to fetch gold and silver, precious stones and ivory. Though scholars disagree on exactly where Ophir was, the evidence points to India. Thus, India’s reputation as a land of riches predates the Roman Empire by centuries. By the time the Romans were masters of the western world they were anxious to seek her wealth and bring it home.
The treasures of India and Western myths
Fabulous treasures often breed fabulous ideas. In the pre-scientific ages nearly any account told by travelers and traders was accepted at face value. Miners and sellers of precious minerals did not want to reveal their sources, so they fabricated stories about how they found them. As these tales were passed around, they acquired the air of truth. The days of systematic exploration were still far off. Stories which only make us smile today were once widely believed. They explained the sources of precious materials in an entertaining and satisfying way, often emphasizing the dangers involved in securing the earth’s riches, the better to ward off would be poachers and thereby inflate prices.
The Romans believed that Indian gold was dug by ants. India has long been a gold importer, but also produced gold of its own. The gold mines near Hutti in southern India go back to this age, and old shafts go down to 250 feet (80 meters). The mines near Kolar, also in southern India, may not be that old, but have been worked so long and are so deep (up to 650 feet or 200 meters) that today they are being used for an experiment by physicists to determine whether protons, one of the constituents of atoms, every decay. These experiments must be carried out in deep mines to shield the sensitive equipment from cosmic rays, and the abandoned Kolar gold mines are perfect for this purpose.
But the Romans knew nothing about nuclear physics; they believed that insects mined gold in India. The historian Herodotus said that ants bigger than foxes brought up gold nuggets the size of walnuts while building their hill. Men had to get the gold during the hottest part of the day so that the ants would be in their burrows. The ants could smell the men coming to steal their gold, and would rush out to chase them away.
How did such a story get is start? We cannot say for sure, but it is possible that ants have brought up small pieces of gold while constructed their homes. A common archaeologists’ trick is to examine ant hills because the inhabitants sometimes excavate beads and other small artifacts from under the surface. Maybe somewhere the tiny, hardworking insects brought up enough gold to start the legend of the gold digging ants? Unlikely, and scholars also suggest that a linguistic confusion is responsible for the legend. Gold sent to India from Tibet was once called paipilika gold, while the gold supposedly dug by the ants were known as pipilikia gold. Maybe the gold digging ants were really Tibetans.
Beryl and diamonds, pearl and coral
As eager as the Romans were for gold, they were even more infatuated with beryl and pearls. India was glad to supply both.
The Roman savant Pliny in his Natural History said that beryls came only from India. There he believed they were all shaped into hexagonal prisms, though some authorities claimed that was their natural form. The Indians pierced them and strung them on elephant hairs.
Beryls were very special because they were the hardest materials that could be made into beads, harder than virtually any mineral except the corundum gems and diamond. Of course, the beryl beads were not formed by men; the natural hexagonal crystal shape was retained, and they were merely drilled lengthwise to be strung. The beryl mines of India were located in Coimbatore district in the south. So important was this industry that the largest hoards of Roman gold coins in India have been found there. This fact alone speaks for the tremendous demand for beryls in the Roman Empire and the gravitational pull of the mining area for Roman money.
The other secret in the export of beryl beads was that India could drill them despite their hardness. This calls for a diamond, and India was the principal source of diamonds for a long time. It is uncertain how long they were known in India, but the Rig Veda, the oldest book in the world (about 1500 B.C), mentions vajra, the thunderbolt with which the god Indra slew his enemies. Some 700 years later in the Atharva Veda, vajra had become a minor deity, the chief of the scathers, doing more than harm to enemies than any other god. Vajra could cut even the mythical Asuras, who bound men by slinging iron nets around them. The word vajra in later Sanskrit means diamond. Was the god Vajra of the Atharva Veda also a diamond, able to cut the Asuras iron nets? If this is correct, it means that the Indians recognized the cutting power of diamonds quite early.
In any case, the Indians were the first to use diamonds industrially. Double-tipped diamond drills were used to perforate quartz and chalcedonies at Arikamedu, in southeast India, occupied from the third century B.C to the third century A.D and it seems that all stone beads there were perforated with these drills. This use was recognized in the Greek and Roman world at least by the first century A.D. The earliest reference to diamonds in China was in A.D 114; they were first called chin-kang, which means gold hard or metal hard, the Chinese rendering of vajra.
The early literature on diamond is full of myths. Epiphanius, a fourth century bishop of Cyprus, was first to relate that diamonds were found only in one valley densely inhabited by poisonous snakes. To retrieve them, men threw pieces of meat down and eagles swooped in and took the meat to their nests. Diamonds stuck to the meat when it landed on the valley floor, and could be retrieved (though not without considerable risk) by killing the eagles or raiding their nests. The story became widely circulated. It is found in Chinese texts by 510 A.D, was part of the lore of the Arab hero, Sinbad the Sailor, and was recounted by Marco Polo 900 years later. Some scholars have suggested that it echoed sacrificing an animal before looking for diamonds, but this has no basis in fact. It seems more likely that it was a tale circulated by the Indians to discourage outsiders from raiding the mines.
Roman women (and a few men, much to Pliny’s disgust) adored pearls. Pearls are found in the Persian Gulf, but also along the southern Indian coast, especially in the Palk Strait and Gulf of Mannar. There are no accounts from Roman times as to how the pearl fishing was conducted. Marco Polo described the scene in the thirteenth century, and in 1797 Le Beck left a more detailed report. Their accounts are probably similar to the way pearl fishing was done in early times.
The center of activity was the deserted village of Condatchy, which sprung to life during the fishing season. The divers were fishermen from along the Indian coasts. They and merchants, brokers, and common people hoping for sudden wealth converged on Condatchy despite brackish water, the hoards of beggars who followed the crowds, and what was described as overpoweringly disagreeable odors.
The small diving boats held twenty one men: ten to dive, five to handle the diving stones and nets, and six to row. The divers would not enter the water until anti-shark magic was performed. After that, a net attached to a stone was dropped off the boat and the divers held their breath and plunged in. While diving they hung onto the cord that attached the nets and stones to the boats. Each diver stayed under about two minutes, descending fifteen to thirty meters.
The shells were opened on the shore, and the pearls sorted with small perforated brass plates or weighed on scales. Common people bought shells from the brokers to open themselves, hoping for a rich prize. During the 1797 season day laborer paid two pennies for three shells and found one of the biggest pearls of that profitable season.
The men who drilled the pearls made very little money, considering the fortunes they handled, but worked swiftly and deftly. The pearls were put in a hole at the bottom of a small, soft, wooden, up-turned cone which sat atop a short tripod. A metal drill bit hafted in wood was held with the left hand while the right hand worked a small bow back and forth. The worker dipped the little finger of his right hand into water in a coconut shell to drip over the pearl to keep it cool while drilling. The remarkable dexterity needed to perform all these operations at once could only be acquired with long practice.
Though it was well known that pearls came from oysters, there was still an air of mystery surrounding them. Aristotle thought that pearls were oyster hearts, and the Roman polymath, Pliny, wrote that oysters would “Yawn and gape…(then) conceive a certain moist dew as (sperm)..and the fruit of these shellfish are pearls.” Centuries later there were still questions about oysters: Did they walk on the sea floor? Were pearls soft in the shell?
The gem trade between Roman and India was not entirely a one-way street. The Romans controlled a material which the Indians found particularly desirable: precious red coral. A Greek sailor of the first century wrote about his voyages in The Periplus of the Erythraean Sea, telling us that Roman coral from the Mediterranean was much in demand in India and China, where it was used for ornaments and various medicinal purposes.
In Roman times coral was the major trade product going from Europe to Asia. Indians had been in love with coral long before Roman contact, and stayed in love with it longer after the Romans had gone. It was a staple of commerce between medieval Egypt and India. When the French jeweler, Jean Baptiste Tavernier, visited India in the seventeenth century, he noted that though coral was only semiprecious in Europe, it was precious in India and to the north. Even in the early twentieth century India was still the world’s greatest market for the red gem of the sea.
The nature of coral also defied the experts. As late as the seventeenth century, coral was being classified by early botanists as a plant.
The quartz gems
Diamonds, pearls and beryl were eagerly sought in the Roman Empire, and Roman gold coins and coral were welcome in India. These were an important segment of the ancient trade between these great civilizations. However, in terms of sheer bulk these products were only a small part of the ancient East West gem trade. The greatest amount, and in many ways the most important, was in a material not as rare as diamonds or pearls, but still of great beauty. We now regard it as semiprecious, but the ancients made no distinction between precious and semiprecious.
The quartz minerals provide us with more gems and jewels than any other minerals family. The Indian agate gem industry was centered in the west, especially the state of Gujarat. It supplied carnelian to Mesopotamia 2000 years before Romans, and even in our day is the major supplier of such beads worldwide. Along with carnelian, the mines located along the River Narmada, supply banded agate. Both the carnelian and agate nodules are found in a layer of red silt that was deposited with the stones when they were washed out of the Vindhya Mountains aeons ago. The deposition stopped about 22000 years ago. In contact with this red silt, the stones have absorbed iron. When they are heated in a muffled (reducing) furnace the iron turns to red, giving us carnelian and sardonyx. This is the spot that the Roman geographer Ptolemy called “The Sardonyx Mountain.”
There was another important gem cutting center in ancient India, which had close contact with Rome and produced some of the finest semiprecious gem stones ever seen. The Romans called it Podouke (with variations), as close as they could get to the name Puduchcheri, which survives today in the name of a nearby modern city of Pondicherry. The ancient city is now better known as Arikamedu, a name given to the ruined site by the local villagers, meaning “The Mound of Arukan”.
Whatever it was called, Arikamedu was a bustling manufacturing and shipping center in the early centuries A.D. The Romans had an emporium there, a place for Roman merchants to live and do business. Arikamedu manufactured several products the Romans wanted, such as colored cloth and leathered goods. But the real wealth of the city was in gems and costume jewelry of both glass and semiprecious stones. It may well have been an important market for beryls and pearls. Whether these were a large part of the trade is not known, but we do know that the glassmakers of Arikamedu took advantage of the Roman fondness for beryls, imitating precious stones, beryl in particular. It wasn’t that they colored rock crystal, but that they knew to make tubes of glass and paddle them into hexagonal shapes to imitate beryl.
Foremost among these gems trade from Arikamedu was onyx for Roman cameos, small carvings in low relief on a material with differently colored layers, which leaves figures against a contrasting background. The Romans were crazy about these handsome jewels. Pliny mentioned their popularity and said that cameo cutting was a new art. This was probably because the sea route to India had been newly opened, and the cameo material was available in bulk for the first time. Cameo production was encouraged by the emperors themselves, and several of the Caesars had magnificent collections of them.
The Arikamedu lapidaries excelled in making fine black and white onyx for these cameos. Onyx is extremely rare in nature. Man has to help out if he wants it. The onyx of Arikamedu began as plain, banded grey and white agate. The grey bands are more porous than the white, and when agate is soaked in a sugar solution or honey, it absorbs some sugar. When the stone is heated afterwards, the sugar carmelizes, leaving brown and white bands. If it is put into sulphuric acid, the sugar is carbonized, making black and white onyx.
Arimamedu was apparently the first place to make black onyx. The lapidaries sold much of it to Rome. They used it themselves to cut beads and other products, including thin-walled onyx bowls or cups, but most of the onyx found in the archaeological site was made into flat pieces, ellipsoidal in shape, suitable only for cameo cutting.
Turning agate into onyx was not the only trick the Arikamedu beadmakers knew. Another favorite stone was amethyst; many beautiful amethyst beads have survived made in a lively style with an excellent technique. Poor quality amethyst can be treated to produce a different gemstone altogether. By firing amethyst in a complex process, the golden yellow citrine results. Again Arikamedu seems to be the first place citrine was made, and the stone took its place along others as a major raw material for beads and gems.
Other stones were also worked at Arikamedu. Garnets were polished for cabochons to be set into metal jewelry. Rock crystal quartz and carnelian were very popular, and we occasionally find smoky, rose and green crystal quartz, jasper and opal used for beads. The semi-translucent green prase was also cut in quantity.
The fourth century Greek geographer Dionysius Periegetes must have had Arikamedu in mind when he wrote, “Among the courses of mountain torrents (the Indians) search for precious stones, the green beryl, or the sparkling diamond, or the pale green translucent jasper, or the yellow stone, or the pure topaz, or the sweet amethyst which with milder glow imitates the lure of (royal) purple.” The green jasper and the yellow stone are doublets prase and citrine and, along with the sweet amethyst, were among the most important of Arikamedu’s products.
The raw stones for the Arikamedu lapidaries were not locally available. They were transported hundreds of kilometers from the mouths of the Krishna and Godavari Rivers on the east coast of India or from inland areas. Though the stones traveled before they reached Arikamedu, the trip would be nothing compared to the one they would make after being fashioned and sent to the Roman Empire.
The lapidaries were extremely skillful at their occupation. Beads, cabochons and cameo blanks were made there, as were finger rings, cups or bowls, ear reels and perhaps bangles. All these required considerable skill. The bowls/cups, bangles and finger rings were cut out with large diameter drills (perhaps bamboo), aided with abrasives. Circular striations from the rotary motion of the drills can still be seen on unpolished specimens.
Another key aspect of this ancient industry was its organization. One of the most astounding things about Arikamedu is that beads were apparently made to preconceived patterns, not only shape, which we would expect, but even in size. Measurements of the collar beads (with extra material around their apertures) show that some types had very uniform dimensions. One group differed no more than 0.2 and 0.4mm in width and length, while another group differed by only 0.8 and 1.1mm in length and width. Even 1.1 mm, the largest of these differences, is very small. The precision of the Arikamedu lapidaries is evident.
The cameos were not cut into form in India. This was done in the Roman Empire, not because the Indians could not do the exquisite work, but because the Romans insisted on portraits of their own emperors and gods. A few finished seals have been found at Arikamedu, but it is thought that they were made by Roman or Greek artist living there.
The superior craftsmanship and excellent materials employed at Arikamedu are more difficult to describe than to picture, and the best way to appreciate this work is look at the plates accompanying this article. As beautiful as some of the pieces are, however, keep in mind that the finest work was not lost or discarded in the city for archaeologists to uncover 2000 years later, but shipped to the West as an integral part of the ancient and long lived East-West trade in jewels and gemstones.
(via Gemological Digest, Vol.3, No.1, 1990) Peter Francis, Jr writes:
Abstract
The Roman Empire was among the best customers of the ancient world. From outside the Empire she sought items of luxury, especially precious gems. India was pleased to supply the insatiable appetite of the Roman elite. In turn, Rome paid mostly in gold coin, and supplied India with only one desired luxury, coral. The ancient gem trade was characterized by much mystery surrounding the sources of jewels, at least some of it purposeful smoke screen to ward off competition. In addition, there was general ignorance about the nature of gems such as pearls and coral. Even more important than the commerce in what we call precious stones was that in semi precious stones. Recent archaeological work has helped reveal some of the facts of this once thriving Indian industry.
Introduction
To the ancient Romans, the East, especially India, was the depository of all wealth. The Indians not only sold her mineral treasures to Rome, but were leaders in developing technologies that allowed them to be exploited.
Just over 2000 years ago the sea-faring Arabs taught Roman sailors an important secret: how to sail through the Erythraean or Red Sea, which then included the whole of the western Indian Ocean. The secret involved understanding the predominant wind patters by which ships could sail from west to east for a few months and then back from east to west during the other half of the year. This took advantage of the famous trade winds.
In those days Rome was the greatest power in the West. Aristrocrats were only politically ascendant, but also fabulously wealthy. They demanded objects that could prove their wealth beyond doubt, especially those for ostentatious display. For a very long time the best way to show off wealth has been to wear jewelry. Precious stones set in precious metals and worn by the precious few are a principal means of demonstrating that one has arrived and is rich, whether nouveau or otherwise.
This is why the discovery of a simple sea route to the East was so important to the Romans. Above all, the East meant wealth, treasure, gems and jewels beyond imagination; it was considered the depository of all valuable goods.
There were two mighty empires in the East: China and India. China was a wealthy land but also an impenetrable mystery. Though trade trickled across mountains and deserts between China and Rome, sea routes were long and dangerous and hardly ever used over such a vast distance. The Mediterranean world and China were isolated for centuries, save for the Silk Route, which was periodically closed by Central Asian bandits whenever control was weak in the Middle Kingdom.
But India was different story. A land widely renowned for its treasure, India had long traded luxury products to the western world. Millenia before Rome was built, carnelian and lapis lazuli were sold by the Indus Valley Civilization to the city states of Mesopotamia. King Solomon of Israel around 1000 B.C sent ships to Ophir to fetch gold and silver, precious stones and ivory. Though scholars disagree on exactly where Ophir was, the evidence points to India. Thus, India’s reputation as a land of riches predates the Roman Empire by centuries. By the time the Romans were masters of the western world they were anxious to seek her wealth and bring it home.
The treasures of India and Western myths
Fabulous treasures often breed fabulous ideas. In the pre-scientific ages nearly any account told by travelers and traders was accepted at face value. Miners and sellers of precious minerals did not want to reveal their sources, so they fabricated stories about how they found them. As these tales were passed around, they acquired the air of truth. The days of systematic exploration were still far off. Stories which only make us smile today were once widely believed. They explained the sources of precious materials in an entertaining and satisfying way, often emphasizing the dangers involved in securing the earth’s riches, the better to ward off would be poachers and thereby inflate prices.
The Romans believed that Indian gold was dug by ants. India has long been a gold importer, but also produced gold of its own. The gold mines near Hutti in southern India go back to this age, and old shafts go down to 250 feet (80 meters). The mines near Kolar, also in southern India, may not be that old, but have been worked so long and are so deep (up to 650 feet or 200 meters) that today they are being used for an experiment by physicists to determine whether protons, one of the constituents of atoms, every decay. These experiments must be carried out in deep mines to shield the sensitive equipment from cosmic rays, and the abandoned Kolar gold mines are perfect for this purpose.
But the Romans knew nothing about nuclear physics; they believed that insects mined gold in India. The historian Herodotus said that ants bigger than foxes brought up gold nuggets the size of walnuts while building their hill. Men had to get the gold during the hottest part of the day so that the ants would be in their burrows. The ants could smell the men coming to steal their gold, and would rush out to chase them away.
How did such a story get is start? We cannot say for sure, but it is possible that ants have brought up small pieces of gold while constructed their homes. A common archaeologists’ trick is to examine ant hills because the inhabitants sometimes excavate beads and other small artifacts from under the surface. Maybe somewhere the tiny, hardworking insects brought up enough gold to start the legend of the gold digging ants? Unlikely, and scholars also suggest that a linguistic confusion is responsible for the legend. Gold sent to India from Tibet was once called paipilika gold, while the gold supposedly dug by the ants were known as pipilikia gold. Maybe the gold digging ants were really Tibetans.
Beryl and diamonds, pearl and coral
As eager as the Romans were for gold, they were even more infatuated with beryl and pearls. India was glad to supply both.
The Roman savant Pliny in his Natural History said that beryls came only from India. There he believed they were all shaped into hexagonal prisms, though some authorities claimed that was their natural form. The Indians pierced them and strung them on elephant hairs.
Beryls were very special because they were the hardest materials that could be made into beads, harder than virtually any mineral except the corundum gems and diamond. Of course, the beryl beads were not formed by men; the natural hexagonal crystal shape was retained, and they were merely drilled lengthwise to be strung. The beryl mines of India were located in Coimbatore district in the south. So important was this industry that the largest hoards of Roman gold coins in India have been found there. This fact alone speaks for the tremendous demand for beryls in the Roman Empire and the gravitational pull of the mining area for Roman money.
The other secret in the export of beryl beads was that India could drill them despite their hardness. This calls for a diamond, and India was the principal source of diamonds for a long time. It is uncertain how long they were known in India, but the Rig Veda, the oldest book in the world (about 1500 B.C), mentions vajra, the thunderbolt with which the god Indra slew his enemies. Some 700 years later in the Atharva Veda, vajra had become a minor deity, the chief of the scathers, doing more than harm to enemies than any other god. Vajra could cut even the mythical Asuras, who bound men by slinging iron nets around them. The word vajra in later Sanskrit means diamond. Was the god Vajra of the Atharva Veda also a diamond, able to cut the Asuras iron nets? If this is correct, it means that the Indians recognized the cutting power of diamonds quite early.
In any case, the Indians were the first to use diamonds industrially. Double-tipped diamond drills were used to perforate quartz and chalcedonies at Arikamedu, in southeast India, occupied from the third century B.C to the third century A.D and it seems that all stone beads there were perforated with these drills. This use was recognized in the Greek and Roman world at least by the first century A.D. The earliest reference to diamonds in China was in A.D 114; they were first called chin-kang, which means gold hard or metal hard, the Chinese rendering of vajra.
The early literature on diamond is full of myths. Epiphanius, a fourth century bishop of Cyprus, was first to relate that diamonds were found only in one valley densely inhabited by poisonous snakes. To retrieve them, men threw pieces of meat down and eagles swooped in and took the meat to their nests. Diamonds stuck to the meat when it landed on the valley floor, and could be retrieved (though not without considerable risk) by killing the eagles or raiding their nests. The story became widely circulated. It is found in Chinese texts by 510 A.D, was part of the lore of the Arab hero, Sinbad the Sailor, and was recounted by Marco Polo 900 years later. Some scholars have suggested that it echoed sacrificing an animal before looking for diamonds, but this has no basis in fact. It seems more likely that it was a tale circulated by the Indians to discourage outsiders from raiding the mines.
Roman women (and a few men, much to Pliny’s disgust) adored pearls. Pearls are found in the Persian Gulf, but also along the southern Indian coast, especially in the Palk Strait and Gulf of Mannar. There are no accounts from Roman times as to how the pearl fishing was conducted. Marco Polo described the scene in the thirteenth century, and in 1797 Le Beck left a more detailed report. Their accounts are probably similar to the way pearl fishing was done in early times.
The center of activity was the deserted village of Condatchy, which sprung to life during the fishing season. The divers were fishermen from along the Indian coasts. They and merchants, brokers, and common people hoping for sudden wealth converged on Condatchy despite brackish water, the hoards of beggars who followed the crowds, and what was described as overpoweringly disagreeable odors.
The small diving boats held twenty one men: ten to dive, five to handle the diving stones and nets, and six to row. The divers would not enter the water until anti-shark magic was performed. After that, a net attached to a stone was dropped off the boat and the divers held their breath and plunged in. While diving they hung onto the cord that attached the nets and stones to the boats. Each diver stayed under about two minutes, descending fifteen to thirty meters.
The shells were opened on the shore, and the pearls sorted with small perforated brass plates or weighed on scales. Common people bought shells from the brokers to open themselves, hoping for a rich prize. During the 1797 season day laborer paid two pennies for three shells and found one of the biggest pearls of that profitable season.
The men who drilled the pearls made very little money, considering the fortunes they handled, but worked swiftly and deftly. The pearls were put in a hole at the bottom of a small, soft, wooden, up-turned cone which sat atop a short tripod. A metal drill bit hafted in wood was held with the left hand while the right hand worked a small bow back and forth. The worker dipped the little finger of his right hand into water in a coconut shell to drip over the pearl to keep it cool while drilling. The remarkable dexterity needed to perform all these operations at once could only be acquired with long practice.
Though it was well known that pearls came from oysters, there was still an air of mystery surrounding them. Aristotle thought that pearls were oyster hearts, and the Roman polymath, Pliny, wrote that oysters would “Yawn and gape…(then) conceive a certain moist dew as (sperm)..and the fruit of these shellfish are pearls.” Centuries later there were still questions about oysters: Did they walk on the sea floor? Were pearls soft in the shell?
The gem trade between Roman and India was not entirely a one-way street. The Romans controlled a material which the Indians found particularly desirable: precious red coral. A Greek sailor of the first century wrote about his voyages in The Periplus of the Erythraean Sea, telling us that Roman coral from the Mediterranean was much in demand in India and China, where it was used for ornaments and various medicinal purposes.
In Roman times coral was the major trade product going from Europe to Asia. Indians had been in love with coral long before Roman contact, and stayed in love with it longer after the Romans had gone. It was a staple of commerce between medieval Egypt and India. When the French jeweler, Jean Baptiste Tavernier, visited India in the seventeenth century, he noted that though coral was only semiprecious in Europe, it was precious in India and to the north. Even in the early twentieth century India was still the world’s greatest market for the red gem of the sea.
The nature of coral also defied the experts. As late as the seventeenth century, coral was being classified by early botanists as a plant.
The quartz gems
Diamonds, pearls and beryl were eagerly sought in the Roman Empire, and Roman gold coins and coral were welcome in India. These were an important segment of the ancient trade between these great civilizations. However, in terms of sheer bulk these products were only a small part of the ancient East West gem trade. The greatest amount, and in many ways the most important, was in a material not as rare as diamonds or pearls, but still of great beauty. We now regard it as semiprecious, but the ancients made no distinction between precious and semiprecious.
The quartz minerals provide us with more gems and jewels than any other minerals family. The Indian agate gem industry was centered in the west, especially the state of Gujarat. It supplied carnelian to Mesopotamia 2000 years before Romans, and even in our day is the major supplier of such beads worldwide. Along with carnelian, the mines located along the River Narmada, supply banded agate. Both the carnelian and agate nodules are found in a layer of red silt that was deposited with the stones when they were washed out of the Vindhya Mountains aeons ago. The deposition stopped about 22000 years ago. In contact with this red silt, the stones have absorbed iron. When they are heated in a muffled (reducing) furnace the iron turns to red, giving us carnelian and sardonyx. This is the spot that the Roman geographer Ptolemy called “The Sardonyx Mountain.”
There was another important gem cutting center in ancient India, which had close contact with Rome and produced some of the finest semiprecious gem stones ever seen. The Romans called it Podouke (with variations), as close as they could get to the name Puduchcheri, which survives today in the name of a nearby modern city of Pondicherry. The ancient city is now better known as Arikamedu, a name given to the ruined site by the local villagers, meaning “The Mound of Arukan”.
Whatever it was called, Arikamedu was a bustling manufacturing and shipping center in the early centuries A.D. The Romans had an emporium there, a place for Roman merchants to live and do business. Arikamedu manufactured several products the Romans wanted, such as colored cloth and leathered goods. But the real wealth of the city was in gems and costume jewelry of both glass and semiprecious stones. It may well have been an important market for beryls and pearls. Whether these were a large part of the trade is not known, but we do know that the glassmakers of Arikamedu took advantage of the Roman fondness for beryls, imitating precious stones, beryl in particular. It wasn’t that they colored rock crystal, but that they knew to make tubes of glass and paddle them into hexagonal shapes to imitate beryl.
Foremost among these gems trade from Arikamedu was onyx for Roman cameos, small carvings in low relief on a material with differently colored layers, which leaves figures against a contrasting background. The Romans were crazy about these handsome jewels. Pliny mentioned their popularity and said that cameo cutting was a new art. This was probably because the sea route to India had been newly opened, and the cameo material was available in bulk for the first time. Cameo production was encouraged by the emperors themselves, and several of the Caesars had magnificent collections of them.
The Arikamedu lapidaries excelled in making fine black and white onyx for these cameos. Onyx is extremely rare in nature. Man has to help out if he wants it. The onyx of Arikamedu began as plain, banded grey and white agate. The grey bands are more porous than the white, and when agate is soaked in a sugar solution or honey, it absorbs some sugar. When the stone is heated afterwards, the sugar carmelizes, leaving brown and white bands. If it is put into sulphuric acid, the sugar is carbonized, making black and white onyx.
Arimamedu was apparently the first place to make black onyx. The lapidaries sold much of it to Rome. They used it themselves to cut beads and other products, including thin-walled onyx bowls or cups, but most of the onyx found in the archaeological site was made into flat pieces, ellipsoidal in shape, suitable only for cameo cutting.
Turning agate into onyx was not the only trick the Arikamedu beadmakers knew. Another favorite stone was amethyst; many beautiful amethyst beads have survived made in a lively style with an excellent technique. Poor quality amethyst can be treated to produce a different gemstone altogether. By firing amethyst in a complex process, the golden yellow citrine results. Again Arikamedu seems to be the first place citrine was made, and the stone took its place along others as a major raw material for beads and gems.
Other stones were also worked at Arikamedu. Garnets were polished for cabochons to be set into metal jewelry. Rock crystal quartz and carnelian were very popular, and we occasionally find smoky, rose and green crystal quartz, jasper and opal used for beads. The semi-translucent green prase was also cut in quantity.
The fourth century Greek geographer Dionysius Periegetes must have had Arikamedu in mind when he wrote, “Among the courses of mountain torrents (the Indians) search for precious stones, the green beryl, or the sparkling diamond, or the pale green translucent jasper, or the yellow stone, or the pure topaz, or the sweet amethyst which with milder glow imitates the lure of (royal) purple.” The green jasper and the yellow stone are doublets prase and citrine and, along with the sweet amethyst, were among the most important of Arikamedu’s products.
The raw stones for the Arikamedu lapidaries were not locally available. They were transported hundreds of kilometers from the mouths of the Krishna and Godavari Rivers on the east coast of India or from inland areas. Though the stones traveled before they reached Arikamedu, the trip would be nothing compared to the one they would make after being fashioned and sent to the Roman Empire.
The lapidaries were extremely skillful at their occupation. Beads, cabochons and cameo blanks were made there, as were finger rings, cups or bowls, ear reels and perhaps bangles. All these required considerable skill. The bowls/cups, bangles and finger rings were cut out with large diameter drills (perhaps bamboo), aided with abrasives. Circular striations from the rotary motion of the drills can still be seen on unpolished specimens.
Another key aspect of this ancient industry was its organization. One of the most astounding things about Arikamedu is that beads were apparently made to preconceived patterns, not only shape, which we would expect, but even in size. Measurements of the collar beads (with extra material around their apertures) show that some types had very uniform dimensions. One group differed no more than 0.2 and 0.4mm in width and length, while another group differed by only 0.8 and 1.1mm in length and width. Even 1.1 mm, the largest of these differences, is very small. The precision of the Arikamedu lapidaries is evident.
The cameos were not cut into form in India. This was done in the Roman Empire, not because the Indians could not do the exquisite work, but because the Romans insisted on portraits of their own emperors and gods. A few finished seals have been found at Arikamedu, but it is thought that they were made by Roman or Greek artist living there.
The superior craftsmanship and excellent materials employed at Arikamedu are more difficult to describe than to picture, and the best way to appreciate this work is look at the plates accompanying this article. As beautiful as some of the pieces are, however, keep in mind that the finest work was not lost or discarded in the city for archaeologists to uncover 2000 years later, but shipped to the West as an integral part of the ancient and long lived East-West trade in jewels and gemstones.
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