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The Accredited Gemologists Association 2008 Tucson Conference

By Stuart M. Robertson, GG

Demo at 2008 Conference

Speaker at 2008 conference

Networking at 2008 Conference

This year’s AGA Tucson event tackled a series of treatment related issues through the kind of first class line-up of speakers and hands-on lab sessions that have come to define this annual event. The morning kicked off with a panel discussion on new treatments and their detection, moderated by Colored Stone Magazine’s David Federman. The panelists included Ted Themelis, GemLab, Inc., Bangkok, Kevin Bennett, Azotic Coating Technology, and Dr. Michael Schlamadinger, D. Swarovski & Co.

Themelis provided a sobering view of the current state of the industry. He reminded the audience that he had appeared before the AGA five years ago to discuss the diffusion of light elements into corundum. “Today that process has progressed to include heavy elements including Lanthanum.” This is having a radical affect on the appearance of stones. Themelis explained that his peers in Thailand are treating 2 to 3 million carats of corundum a month this way, much of it low-grade unsalable material before the process.

This gave further cause for Federman to note that the language used to describe gems and disclose treatments in today’s market is simply no longer adequate. “This is no longer a denotation of a gem. The product codes no longer serve the industry. It is too antiquated and must be updated. This trade is applying ‘natural’ to stones that are composite stones held together by fillers. To label these products as ‘treated’ is a joke…it is ludicrous. The alteration is too extreme. This industry has been brought to the brink of catastrophe. Deny it all you want, but treatments are ragging out of control.”

The world of diamonds & colored gemstones is constantly changing, & in particular, the acceptance of treated gemstones in the marketplace. More gemstone varieties are being treated than ever before, in many new ways. But not all treatments are equal in terms of permanence & impact on value. It is increasingly difficult for buyers & sellers to know for sure what they are buying & selling since many dealers don’t know themselves.

The conference begins with an examination & discussion of new types of treatments & detection methods. Following the presentations are hands-on activities plus an innovative presentation on ways independent gemologists can get the most out of classic gemological techniques.

Themelis cautioned that more treatments are on the way. From his Thailand based treatment and research laboratory, he has had a perfect view of changes in the global trade. And what he has witnessed during the past few years had him confident in his statement “The Thai treaters stay several layers ahead of the labs in the treatment vs. detection challenge.”

With the microphone passed to Azotic Coating’s Bennett, he took the opportunity to discuss his company’s product in detail. He described the history of the company followed by the treatment, including details of their vacuum deposition process. They currently treat topaz, CZ and quartz among a few others. In a similar fashion, Schlamadinger discussed Swarovski products in detail. They too are using a coating process to treat some of their material.

Following that program, representatives form the laboratory community offered information on identifying new treatments. This panel consisted of Dr. Lore Kiefert, Director, AGTA-Gem Testing Center, Christopher Smith, Vice President, AGL, Branko Deljanin, EGLUSA, and Dr. James Shigley, GIA Distinguished Research Fellow.

Kiefert discussed practical techniques for identifying coatings. She focused on products from the three main producers supplying the market, Azotic, Leslie (acquired by Swarovski & Co.) and Swarovski. Each process was discussed, with contrast drawn between their similarities and differences to assist in distinguishing each from the other.

AGL’s Smith focused on a new diffusion process for blue sapphire that was claimed to involve beryllium. However, his research demonstrated it to be a cobalt diffusion confined to the surface of the stone. Identification is not a challenge with careful examination of sapphires in microscope in defused light. Immersion also showed the coloration to be confined to the surface or concentrated in healed fractures and following fractures. Color also tended to be homogenous in the stone, which when combined with evidence of extreme heating conditions should suggest a more careful look at stone.

EGL’s Deljanin provided the results of EGLUSA’s research on synthetic, treated and natural pink diamonds. The presenter offered useful clues to testing and separating these products in this interesting lecture. The study was based on a large population representing the more important diamond deposits. Branko also demonstrated how cross-polarized filters could be used to quickly and reliably separate synthetic pink melee.

Dr. Shigley’s program suggested that coating treatments run the full gambit with some of this technology producing stones that can be far more challenging to detect than previously believed. He discussed coating technology as it pertains to diamonds. Among the processes, Shigley discussed was the Serenity Coating Process used to create fancy colors in diamond. He also noted that GIA has encountered coatings including the diamond like carbon (DLC) on pearls as well as other softer gems. Shigley cautioned that carbon coatings can be difficult to detect and that GIA will continue to share its findings with the industry through similar forums and in their periodicals.

The afternoon sessions were equally informative and focused on ways that gemologists can better use standard gemological equipment and get more information from standard testing techniques using the classic instruments most possess.

When it comes to innovations through classic equipment the first presenter Alan Hodgkinson of the Scottish Branch of Gem-A, has no equal. To the delight of the audience, Alan shared techniques for improved RI readings of opaque gem materials by using top and side lighting techniques to illuminate the stone. He also discussed the use of cross polarizing plates to separate synthetic opal, which is increasingly common in the market. Alan also discussed current state of the synthetic emerald trade and provided tips for using the Hodgkinson Emerald Filters in separating these products from natural and one another.

The last session of the day was a panel discussion entitled “New Lighting Technology & Its Potential Impact on Color Grading Fluorescent Diamonds.” This was a controversial subject to say the least. The panelists included Ronnie Geurtz, Research and Development GIA, Peter Yantzer, Executive Director AGS Laboratories, Jack Ogden, CEO, Gemmological Association of Great Britain, Tom Tashey, CEO, Professional Gem Sciences, diamond dealer Sheldon Kwiat, President, Kwiat Inc., and Stanley Hogrebe, Chairman, Dazor Lighting. The moderator was Gary Roskin, Gemstone Editor, JCK.

This discussion gave an in-depth look into color grading of diamonds. It became clear that there is no single standard for the lighting requirements for color grading. Some labs filter out the UV content emitted by the popular lamps used in this exercise while others do not. The result is that those that do filter out this property are placed at a disadvantage as their grades are viewed as too harsh, especially in the case of fluorescent diamonds. Tom Tashey explained that at PGS, diamonds are graded through the pavilion using white and off white grading trays. This is done to limit the influence that would otherwise result from the fluorescent property of these diamonds. He also noted that on their reports they not only provide the letter grade but also a verbal description of the stones color.

Hogrebe discussed advances in lighting technology and the use of LED light systems. He discussed his research of lighting requirements in use today verses those used in the past for diamond grading. He noted that earlier writings by Liddicoat and Shipley indicated that diamonds should be graded in a UV free environment, a position apparently not held by GIA today. The lone diamond dealer of the panel, Sheldon Kwiat expressed concern that changing standards for lighting could create confusion in the market and prohibit repeatability in achieving the same grade on the same diamond at different periods in time.

The AGA conference is one of the highlights of the Tucson Gem Show experience. The conference concludes with the annual dinner Gala and awarding of the coveted Antonio C. Bonanno Award for Excellence in Gemology. This year’s honoree was Dr. James Shigley, Distinguished Research Fellow at the GIA, Carlsbad, CA.

Reprinted by permission of The Guide, GMN

This program was held on February 6, 2008.

 


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