The Gemworld International team, headed by Richard Drucker, hosted the fifth World of Gems Conference September 23–24 at the Loews Hotel in Chicago. The event was bookended by optional classes, making it an ideal opportunity for attendees to learn about new topics from a diverse group of international speakers (see above) and brush up on their practical gemology skills. Between presentations, the conference held its first-ever poster session. The posters included interactive discussions on jet and the identification of light blue stones using the polariscope and the conoscope, hosted by Sarah Caldwell Steele (Ebor Jetworks, Whitby, United Kingdom) and Kerry Gregory (Gemmology Rocks, Weavering, United Kingdom), respectively.
Invited speaker Emmanuel Fritsch (University of Nantes, France) opened with a talk about the identification of melee synthetic diamonds. He noted that while the majority of specimens are not hard to identify, near-colorless HPHT-treated synthetic melee may still be challenging. Dr. Fritsch also provided a brief history of synthetic diamond production and the current state of the industry, as well as basic and advanced methods of separating synthetic from natural. Isotropy and anomalous double refraction—otherwise known as strain—were covered in some detail, as he considered these very useful identification aids. Jon Phillips (Corona Jewellery Co., Toronto) reviewed world diamond production and the output of mines such as Jwaneng in Botswana, which accounts for 15% of total global production. Meanwhile, Canada’s five operating mines rank among the top 19 producers. One key takeaway from his talk was that De Beers plans to invest US$140 million on a marketing campaign aimed at women buying diamond jewelry for themselves. This should not be ignored by jewelers. Mr. Phillips also reflected on the threat of synthetic melee in the market. This author (GIA, Bangkok) reviewed the different types of pearls (nacreous and non-nacreous) seen in the market and the various mollusks that produce them. The presentation detailed the surface structures of a wide selection of non-nacreous pearls and concluded with a summary of the more frequently encountered treatments. Roland Schluessel (Pillar & Stone International, San Francisco) provided a comprehensive look at Burmese jadeite and defined the various types, including the term fei cui (kingfisher) for the vivid green variety. He examined cultural aspects and discussed factors such as grain size and orientation, which relate to transparency and overall quality. Mr. Schluessel also provided insight into the different colors and patterns, as well as the differences between omphacite and jadeite. Ҫiğdem Lüle and Stuart Robertson (Gemworld International, Glenview, Illinois) reported on various gem treatments that provide enough supply to satisfy market demand. Frequently encountered treatments and the pricing of untreated vs. treated material were reviewed. Diamond was offered as an example of a gem where treatments markedly affect the end value, while tanzanite shows little if any price difference between natural and treated material. A very lively presentation from Kerry Gregory about the daily happenings in the pawnbroking world rounded out day one. Ms. Gregory discussed some of her experiences saving valuable pieces that would have otherwise been destroyed due to lack of resources, training, and time. She also provided insight into her use of simple yet valuable gemological methods (such as the polariscope and conoscope) in identifying light blue stones removed from items destined for the melt.
J.C. (Hanco) Zwaan (Netherlands Gemmological Laboratory, Leiden) started the second day with a comprehensive look at the geological formation and gemological characteristics of metamorphic sapphires from Sri Lanka and to a lesser extent Montana. The search for a primary sapphire deposit in Sri Lanka and the discovery at Wellawaya (which Dr. Zwaan was involved with) were illustrated. Subsequent discussions on the use of chemical plotting in the separation of Sri Lankan and Montana material, from one another and from other sources, showed that it is beneficial but care is still needed with some cases that may overlap. Ҫiğdem Lüle followed with a solo talk about the various natural and “non-natural” black gem materials and the limitations encountered when testing such materials. She covered black diamonds in some detail, outlining the differences between the rare naturally colored stones and heated or irradiated specimens. Al Gilbertson (GIA, Carlsbad) reported on the status of GIA’s fancy-cut diamond grading project and showed the challenges faced when producing a system that takes all variables into consideration and satisfies all opinions. This was reinforced after receiving feedback from 440 participants in six global locations who were asked to look at various fancy cuts and answer a series of questions. Alan Bronstein (Aurora Gems, New York) took attendees on a journey through the colorful world of fancy-color diamonds, looking at the subtleties of the main colors available: yellow, orange, pink, red, green, and blue. Mr. Bronstein was clearly in favor of retaining the original cut of a diamond and not re-cutting it. Chameleon diamonds were also briefly covered. “Beauty trumps rarity” was Mr. Bronstein’s motto. Richard Drucker brought the presentations to a close with a look at some challenges that affect the pricing of gemstones. From the small print in pricing guides that might not be fully understood by users to gemological reports that raise doubts or cause confusion in appraisers’ minds, it became very apparent that the valuation of some colored stones needed careful thought.
The conference ended with a Q&A session in which Mr. Drucker opened the floor to all attendees. Topics such as correct nomenclature and disclosure, brand name cooperation with items submitted for valuation, and color diamond grading consistency were covered.
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