This content was first published on IGR – Italian Gemological Review no. 9 in 2020. The information provided here is therefore current as of the original publication date.
Where does the question of geographical origin lie in gemology? Is this a legitimate subject within its disciplinary scope? Not all the specialists would share the same definition of gemology as well as its ultimate mission or recognize the same boundaries. Yet it is generally agreed upon that basically the original scope of gemology, as a branch of mineralogy, is concerned with the identification of the physical and chemical properties of minerals used as gemstones. At the earlier stage identifying treatments proved to be soon one of the main objectives and this is explained by the inherent bond gemology historically maintains with the market and the need to protect and consolidate the economic value of gemstones. Only in recent times the indication of gemstones’ site of origin gained momentum and became the focal point and the advanced research frontline of the most important laboratories. This requires significant investments and ambitious programs, raising at the same time some wider issues.
The emergence of the gemstone origin issue
As far back as the ‘50s E. J. Gübelin began to be involved with locating the original mining sites of valuable gemstones. But only in the ‘80s he and other researchers started conducting a specific work on the distinctive characteristics of gemstones in order to assess the distinct territories where they originated.
In the beginning, the main working tool was the traditional microscopic investigation and a quick look at the topical Photoatlas books may offer several examples of how the study of the internal features of gems necessarily was already including indications of the geographical origin. Subsequently, chemical and spectroscopic criteria became more and more crucial for the purpose, increasingly involving all the main labs committed to origin determination.
The reason for the spiraling interest with this issue consists in the exponential expansion of the potentially mineral rich areas subject to prospecting that resulted in the extension of gemstone mining activities. The mining industry started to produce marketable gemstones from an increasing number of sources, including unexpectedly gemstone rich locations in Eastern Africa.
There is no such thing as a turning point in time when the importance of origin started to skyrocket in the trade perception. One of the crucial episodes might have been the introduction into the market of the first fine Tanzanian rubies from Winza, initially at very reasonable quotations when compared to the traditionally high priced goods from Myanmar (Figure 2).
Despite the lack of the evocative appeal deriving from that country, a synonym of the finest rubies, African rubies were considered a threat potentially disturbing the market and therefore the trade asked the labs to separate them. Similarly, the industry urged such a distinction in Madagascar for sapphires and emeralds in Afghanistan and Pakistan.
Additionally, the risk of promiscuity among gemstones coming from different mining sites was amplified by the fact that the manufacturing processes generally take place far away from the mining sites and after frequent intermediate transactions. All these reasons explain why the issue of geographic origin emerged so problematic.
Indicatively, an example of how much things had become more complicated for gemologists is provided by the shocking new awareness regarding the iconic three-phase inclusion image traditionally used to indicate the unquestionable Colombian origin of emeralds. In 2014 Gems & Gemology released a research study showing that emeralds from Afghanistan (Panjshir Valley), China (Davdar), and Zambia (Kafubu and the new deposit of Musakashi) may contain three-phase inclusions resembling those often found in specimens from Colombian deposits (Figure 3). The microscope was not sufficient anymore if a confirmation was still to be provided. At least UV-Vis-NIR (Ultraviolet-Visible-Near Infrared) and EDXRF (Energy-Dispersive X-Ray Fluorescence) spectroscopy, if not even in limit cases LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) trace element analysis, were required to attain the origin determination of such emeralds.
It should also be noted that in more recent times tracing the geographical origin in a univocal way is a need that is emerging for ethical policies of responsible sourcing as well. In this case, the territorial indication is originally marked with modern technologies such as the Provenance Proof developed by Gübelin1, a technique IGR has already accounted for (see Issue no. 1, May 2017).
In spite of the establishment of reliable reference samples origin determination remains just an opinion
As in the new millennium, the conditions were mature to establish a scientific method to set up the work it was clear that the real core of the research would have been the systematic collection of samples from the mining field. This task inspired nearly 20 years ago the work of Vincent Pardieu, a passionate researcher destined to become currently one of the most influential independent gemologists on the world stage. He introduced the concept of Field Gemology into labs on the assumption that the foundation for good research should be found in a “solid and reliable reference collection” rather than “in samples coming from trustable sources”.
Pardieu’s first steps in specimen collection were taken at the early time of his collaboration with AIGS and Gübelin Gem Lab. Later on he carried out a group of gemologists under the guidance of Ken Scaratt building for GIA, between 2008 to 2017, probably the best and most complete gemstone reference collection ever assembled in a gemological laboratory. Interestingly, the sample collecting procedures fixed by Pardieu are nowadays largely accepted as a standard. They focus on codified grades of how reliable the specimens are, depending on how much direct is the surveillance of field gemologists in charge and on how far from the mining area they have been collected2.
No doubt GIA, by continuing the expeditions after Pardieu quit, has earned so far a solid reputation as a result of the continuous implementation of a rich and ordered collection of samples from all over the world. This lead to very comprehensive and in-depth coverage published in the Autumn 2019 Gems & Gemology issue entirely dedicated to the theme of gemstone geographic origin.
Significantly, the premises and conclusions of the research carried on by the GIA match what has been agreed by the whole scientific community. In short, given that many cases show the impossibility to trace the provenance from the extraction sites, the origin in gemology can just be expressed as a subjective opinion. Evidently once again we have to take notice that gemology starts where geology comes to a stop. In fact, from a strictly scientific point of view it is more correct setting the occurrence of minerals according to their geological environment rather than to the extraction sites where the mining activities are currently operated.
Geology proves that identical or very similar conditions forming minerals can occur in many countries that are geographically far today but used to be very close to each other in past ages. This is the case of Gondwana (Figure 4), the supercontinent, assembled 600 million years ago, incorporating present-day South America, Africa, Arabia, Madagascar, India, Australia and Antarctica. In this context, as an example, isotopic profound similarities between Sri-Lankan and Madagascar’s high-grade rocks along with other common geological and mineralogical features indicate the early juxtaposition of these areas now about 4,750 km far each other.
Physical geography is a result of the evolution of the geological conditions up to the present time. Therefore while we can distinguish Sri Lanka and Madagascar on the maps of today, we can’t do the same with their respective quite similar metamorphic sapphires. It can be even said that those spatial entities – as we perceive them – just owe their existence to political geography.
Therefore the attempt to assign a geographic tag to gemstones has to do with disciplines related to human sciences such as economy and marketing rather than with quantitative data. In this regard, gemology and political geography share the same relationship with geology as they, while being concerned with studying subjectivity, enter the field of human sciences. Any time gemology gets involved in the actual market environment it must renounce to its claims of objectivity and this is not necessarily a bad thing if supporting the jewelry industry is a function honestly recognized not pretending to be indisputable.
Geographically “branded” gemstones
At this point, first of all, it is appropriate to highlight an issue which, despite being visible to everyone, has never been adequately investigated. Generally precious stones assume their best status only at the end of the manufacturing process as then they will reflect the authority and the reputation of the jewelry brand which set them. But how does a gemological report in practice specifically support the trade, impact on the market and influence the consumers?
Gemological reports find themselves being a powerful vehicle conveying across the entire supply chain not only quantitative data and aesthetic factors but also value connotations. In this perspective, the geographical origin ceases to represent one of the many neutral indications and ends with being the fastest and easiest-to-understand attribute the market needs to immediately make the concept of value understandable to a large public.
Similarly, it has been already noted that an attribute such as “pigeon blood”, while being a useful indication of excellence, also represents a kind of literary term much more appealing and to some degree less innocent than codes or numbers qualifying a certain color of rubies.
Sri-Lanka, Colombia, Kashmir, just to list a few, assume a meaning transcending spatial references and their names become a sort of additional premium that the industry willingly rewards with more generous quotations. It follows that, between two gemstones having similar appearance, color, clarity and cut, there will be one carrying a noticeably higher market value being assigned by the mere evocative call of a location name printed on the world map3.
A typical case is offered by the metamorphic sapphire with possible Myanmar, Sri Lanka or Madagascar origin. Despite in many cases, the laboratories can be quite confident about addressing the origin based on consistent data, it may also happen that there is not enough evidence to make the provenance sure, due to overlapping features.
The geographic gemstone denomination rush has undoubtedly accelerated in recent times under a strong market demand. Understandably the gemstone industry has been more sensitive to this unexpected marketing benefit than to the technical difficulties deriving from borderline cases resulting in divergently subjective opinions.
Apart from the alert raised by SSEF in 2017 about newly discovered Madagascar sapphires from Bemainty/Ambatondrazaka areas indicated in gemological reports as originated in Kashmir, no noticeable inconveniences obviously arose as the gemological reports were provided by just one primary laboratory. Dr. Michael S. Krzemnicki, Director of SSEF, explained very clearly that the Kashmir mistaken origin was not a consequence of overlapping features but of an inadequate assessment corrected by a more careful investigation accomplished through Raman micro-spectrometry, UV-Vis absorption spectroscopy, X-ray fluorescence and LA-ICP-MS trace element analysis. It is just to be noted here how much a documented Kashmir origin would have pleased the market, thirsty for a profitable revival of this virtually extinguished beauty.
However, the geographic attribution proved to work even better at the international jewelry auctions where extra fine stones are supposed to reflect in clear and capital letters their prestige and uniqueness. In this case, since the requested amount goes up, it has become customary that gemstones are accompanied by at least two gemological documents conducive to ascertain their origin. In case discrepancies on the geographical origin emerge, traders will select the most convenient and prestigious one (Figure 5).
The pitfalls are hidden around the corner. Having each lab its proper reference samples and its own investigation systems, discrepancies actually are not unlikely to take place.So it may happen that two or more reports of a metamorphic sapphire, whose origin is to be found in a supposed range including Burma, Sri Lanka and Madagascar coincide on the detected grading objective data while expressing a divergent opinion on the site of extraction. Eventually, for traders the report indicating Myanmar (Burma) will be the most desirable origin choice among the other ones, ensuring a value bonus in response to trade expectations. Ironically if no indication of provenance is provided because of overlapping and not distinctive data, the market will penalize the stone assigning a far lower quotation compared even to the least desired geographic origin. Very much alike the Stock Exchange, fine gem price lists don’t like uncertainty.
Is origin determination within the reach of standard gemology?
It can be useful now to consider the question with the eyes of common gemologists in their ordinary routine. How is the need for geographical determination perceived? What can they actually do, if anything can be done, to duly perform this additional task? First of all, it must be admitted that standard gemology can’t compete with the huge investments developed by the major labs to acquire the sophisticated equipment along with a wide collection of geographically determined rough gem material. Further, these instruments along with the specific testing techniques, being part of proprietary technology every major lab is developing for its own use, are not for free sharing.
Nevertheless, standard gemology can achieve results far beyond what could be reasonably expected only a few years ago. Nowadays the digital divide has reduced thanks to the widespread availability of advanced instrumentation once inaccessible, especially in the field of spectrometry. Much more than in earlier times the identification of gemstone species and varieties as well as treatments fall within the prerogatives of standard gemologists, if properly equipped.
But what to do when it comes to determining the geographical origin? This is a mission that can be challenged, though not all the times accomplished, only by focusing the research on trace elements, though detaining the suitable and sophisticated instrumentation, as we have seen before, would not be sufficient if a reference specimen collection is not available.
EDXRF, the traditional and most widely used instrument for chemical investigation of gemstones is unfit to detect very light elements, thus it has been overcome by LA-ICP-MS whose complicated continual calibration has been exhaustively described in Issue no. 8 of this Review (Winter 2019). It’s no coincidence that the origin determination is carried on by the most influential labs, supported by the costly LA-ICP-MS system.
In conclusion, writing a geographical indication on a report remains an opinion and as such, the stronger is the reputation of the lab, the greater its value is. This new frontier cannot be crossed by small guys running small companies and so, by raising the stakes, distances are restored.
The risk of inconclusive tests
Why, despite the deployment of considerable means, do the exact and univocal identification of the origin of certain precious stones remain occasionally impossible? To explain this it’s necessary to enter into more detailed technical aspects.
Microscopic observation, fluorescence, spectral data offer reliable indications of alleged geological formation. In many cases the standard instrumentation of a reasonably equipped gemologist allows filtering rubies according to iron or chromium content or separating metamorphic from basaltic sapphires. This means that by a lucky combination of hints the geographic origin can be hazarded with reasonable approximation, but of course, this is not always the case.
So the analysis of trace elements in parts per billion should then come to our rescue, in case of corundum Mg, Ti, V, Cr, Fe, Ga and others. It happens that sometimes the trace element profiles are univocal and perfectly match the reference specimens collected in specific mining sites, while sometimes the result is ambiguous and different possible profiles end up overlapping (Figure 7).
Widening the range of the analyzed elements sometimes results in increasing their overlapping while comparing different origins. This is the reason why nowadays focusing on the study of ratios of more elements in combination among them seems to be more important.
Despite all the laboratories that have always been consistent in addressing the origin determination as an opinion only, it seems the message was not fully acknowledged by the market. The effort to detect beryllium diffused into sapphires pushed the bar so high that laboratories as back as 15 years ago had to switch to mass spectrometry and this resulted in an excessively optimistic outlook.
Probably the boost in technical skills that all laboratories had to put in place to deal with the problems of new complicated treatments led the market to believe that unveiling the origin of any gemstone in full all the time without any uncertainty or gray areas was a playable game. As a matter of fact, this flawed perception is starting to cause a feeling of disappointment and lack of trust in labs by many in the industry and, ironically, that is only due to a simple misunderstanding as well as too high expectations.
Conclusion
Definitely the issue of origin, if scientifically dealt with the due diligence, implies considerable economic investments including skilled human resources. At this point, it is almost pleonastic to underline that inadequately equipped gemologists cannot successfully operate given that their competitiveness is dramatically reduced. Furthermore, as a matter of fact in many cases, uncertainty still remains even in spite of the availability of adequate instrumental equipment and representative samples.
Primary gemological laboratories are aware of the possibility that the text box reserved for the geographic origin may remain blank or just report that it is undetectable. It seems that even though this deficiency is correctly recognized among specialists and highlighted in specific studies, an adequate and consequent awareness in the trade and among end consumers has not arisen.
The resurfacing ancient double identity of gemological work should be reconciled by acknowledging the legitimate aspiration of the market to typologically differentiate gems, when this is possible, thanks to their provenance. At the same time, the market should recognize that this additional and subjective information must be related with no exaggeration to the more decisive and objective physical/chemical indications of quality.
Eventually, the fact is that a gemstone origin statement is built exclusively on an opinion and as such, it is considered by the most accredited laboratories. The ultimate question at this point cannot be eluded: can assigning a remarkable economic surplus value to certain gemstones, otherwise identical, relying just on their geographical provenance, be considered ethically acceptable, when by definition no liability can be taken? If the answer to this question is “no” who will have the power and credibility, in addition to a worldwide recognized authority, to convince the whole industry to take a prudent step back on this matter?
Further references:
Dissanayake C.B., Chandrajith R., Sri Lanka-Madagascar Gondwana Linkage: Evidence for a Pan-African Mineral Belt, in : “Journal of Geology”, pp 223.235, 1999, retrieved at: https://www.researchgate.net/publication/249182785_Sri_Lanka-Madagascar_Gondwana_Linkage_Evidence_for_a_Pan-African_Mineral_Belt/citation/download
GEMTOF, Origin Determination, retrieved at: https://www.gemtof.ch/origin-determination
Groat L.A., Giuliani G., Stone-Sundberg J., Sun Z, Renfro N. D., Palke A C., A Review of Analytical Methods Used in Geographic Origin Determination of Gemstones, retrieved at https://www.gia.edu/gems-gemology/winter-2019-analytical-methods-geographic-origin-determination-gemstones
Hughes R.W. , Ruby & Sapphire. A gemologist’s guide. Bangkok, Lotus, 2017
Krzemnicki M. S., Kashmir-like’ sapphires from Madagascar entering the gem trade in large sizes and quantities, retrieved at https://www.ssef.ch/wp-content/uploads/2017/12/SSEF_TRADE_ALERT_-Kashmir-like__sapphires_from_Madagascar__entering_the_gemtrade_in_large_sizes_and.pdf
Lalous G., Investigating the opinion of laboratory reports and geographic origin of gemstones retrieved at: https://gem-a.com/gem-hub/gem-knowledge/laboratory-reports-and-geographic-origin-of-gemstones
McClure S.F., Moses T.M., Shigley J.E., The Geographic Origin Dilemma, retrieved at: https://www.gia.edu/gems-gemology/winter-2019-geographic-origin-dilemma
Pardieu, V., Basic Rules of field Gemology, retrieved on July 21, 2017 at: https://www.fieldgemology.org/blog_display.php?id=90
Saeseaw S., Pardieu V., Sangsawong S. , Three-Phase Inclusions in Emerald and Their Impact on Origin Determination, retrieved at: https://www.gia.edu/gems-gemology/summer-2014-saeseaw-three-phase-inclusions-emerald
V.v.A.a., A holistic method to determining gem origin, retrieved at: https://www.gubelingemlab.com/tl_files/content/03%20Gemmology/Gem%20Lab/Documents/Origin_Article_Sep2006.pdf
Notes
1 The Provenance Proof is an initiative presented by Gübelin Gem Lab in 2018 based on deploying physical tracers, nanoparticles within rough gemstones enabling the supply chain to trace the material starting from the mining sites. This technology, able to ensure the actual origin of the gem material, was tested (paternity test) with emeralds from Zambia in collaboration with Kagem (Gemfields) an subsequently evolved into Provenance Proof Blockchain, a digital ledge, available to the entire industry, in which all the important information of gemstones are secured.
2 The mineral specimens are divided, according to Pardieu and using the description of GIA, as follows: A-type samples are mined directly by the field gemologist; B-type samples are collected at the mine with the field gemologist witnessing the mining process but not actively removing the stones from the ground; C-type samples are collected at the mine but without witnessing the mining process for the specific stones; D-type samples are collected from the miner but not at the mine; E-type samples are purchased from dealers in the local market, often in close proximity to the mines; F-type samples are collected in international markets; Z-type samples are those that have no origin information.
3 In this regard Paraiba, the most valuable and sought for among the copper bearing tourmalines, is a perfect example. Originally these tourmalines were found only in the Brazilian state of Paraiba. More recently Nigeria and Mozambique in Africa have emerged as additional sources.The gemological community recognized that the original trade name Paraiba should be kept for all of them regardless their African or Brazilian provenance. Yet the gem market is assigning a far bigger value to Brazilian Paraiba so much so that geographic origin of them can be successfully determined based on trace elements.
Article by Alberto Scarani and Paolo Minieri, published on IGR – Italian Gemological Review #9, Spring 2020.
