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AGA Tucson Conference was held on Wednesday, February 5, 2014

Gems: Fabulous, Fake, and Nefarious!

The 2014 AGA Tucson Conference promised to be a genuine eye-opener for anyone interested in diamonds and colored gemstones.

Highlights this year included presentations on recent findings pertaining to health hazards associated with green diamonds, the changing world of sapphire from the gems of Burma to the latest composites being sold as genuine, and detailed separation techniques using luminescence for diamonds (natural, treated & synthetic.)

Participants had a rare opportunity to see some of the most important gems in one of the country's finest private colored gemstone collections, and glean important insights into what goes into building such a collection.

Speakers & Topics

Thomas Hainschwang: Hazards of Green Diamonds

Treated green diamonds issued from the trade can at times show extremely high, residual radioactivity. This activity is generally due to irradiation through direct contact with radium salts (usually RaBr2), although this treatment is said to be no longer used. The main purpose of this treatment is to turn diamonds to green, an attractive color, by creating color-centers with the radioactivity energy. Diamonds modified with this method are rare but can potentially represents a serious health risk for consumer's (and gemologists) through direct irradiation by exposure to alpha particles, but also in a less known way, to beta particles and finally in a more dangerous way to high energy gamma rays. Moreover the potential danger these diamonds represent is sometimes increased by the risk of contamination by radium salts residues contained in the open cracks and cavities. Despite the high potential danger of these diamonds, gemological courses curiously do not highlight enough the risk in manipulating them and some gemological articles on the subject shows that the information on radionuclides, and their effects on health, definitely need to be updated.

Note: Franck Notari was unable to join the conference. Thomas graciously stepped in to keep our conference topic on track.

Craig Lynch G.G.: Somewhere in the Rainbow Collection - A World Class Gemstone and Modern Jewelry Collection for your Education & Appreciation

AGA Member Craig Lynch is the gemological consultant to this collection and shared the purpose, scope, and a glimpse at depth of the collection, with time for "hands-on" with several pieces selected from the collection.

Lore Kiefert: In the Footsteps of Dr. Edward Gübelin: Old and New Mogok Mining Methods for Sapphires

For centuries Burma has been regarded as the most important ruby and sapphire source. Gems produced from the area are revered still today. In 2013, Dr. Lore Kiefert, Chief Gemmologist at Gübelin Gem Lab was part of a small group from the lab granted permission to visit the famed Mogok and surrounding gem producing areas as part of a research study. What she found was a fascinating contrast in the characteristics of material collected from classic and newer productions.

The collection of first-hand samples was an important part of this study as Dr. Kiefert had again recently noticed sapphires entering the market, with features which did not fit the range of patterns recognized as being of "Classic" Burmese origin. During this presentation Dr. Kiefert reported on the intensified activities she observed at the mines as well as discussed the gemological characteristics of sapphires produced from newer sources in Burma.

Shane McClure: Titanium Confusion—When Ti-Diffusion is More than Meets the Eye

GIA's Director of Identification Services Shane McClure, an internationally renowned researcher and gemologist, provided attendees with an important update from the GIA lab. McClure's presentation examined the potential for co-diffusion (multiple elements diffusing into a material at the same time) in sapphire. The recent study yielded some fascinating new information concerning the diffusion of titanium in sapphire. The GIA Lab has seen a lot of these sapphires during the last couple of years with a considerable percentage ultimately turning out to be synthetic. This research has uncovered some interesting anomalies concerning the presence of very natural appearing chemistry in the diffused layer of these titanium diffused synthetic sapphires. This presents a potential problem for gemologists relying on chemistry to make a natural/synthetic separation for a clean stone that has been titanium diffused. During his investigation, Shane was able to determine that an older, once standard test can be used to identify these stones. This method was illustrated during the presentation.

Thomas Hainschwang: Luminescence Phenomena in Diamonds and their Importance in Gem Testing

The luminescence colour and distribution can be a good indicator for the origin of colour of a coloured diamond; in order to be capable to perform such distinction one needs enormous experience to be able to know which PL colours belong to which defect, and if this is possible in a naturally coloured diamond or not. Equal or similar luminescence colours can be caused by a variety of defects.  PL spectra are recorded to confirm the nature of the defect and to know certain details such as the widths (FWHM) of emission bands. PL spectroscopy is the most important method to identify HPHT and CVD grown synthetic diamonds and HPHT treated diamonds; this method has the unique capacity to identify extremely low concentrations of defects, far below the detection limit of other spectroscopic methods. Additionally many of the defects detected in diamond by PL spectroscopy cannot be detected by any other means. In consequence luminescence imaging and spectroscopy are two of the most important techniques in diamond analysis.

Olivier Segura: A Journey to the Center of the Pearl: Opportunities, Limits and Challenges of Natural Pearl Analysis

Today, many new types of instrumentation are available that can play an important role in better understanding pearl formation and in accurately identifying natural pearls and distinguishing them for products being erroneously sold as natural pearls. Nonetheless, those laboratories engaged in pearl testing have to face three main challenges:

Natural pearls, and the diversity of mollusks in which they form, constitute a small part of the volume of the all pearls available in today's market, but they represent a huge — and continually increasing — part of the value of pearls sold. ALL participants in the natural pearl trade, including wholesalers, retailers, designers, and those to whom they sell, need to understand the opportunities, limits and challenges of pearl analysis faced by gemological laboratories, and we must all take the time, and understand the importance of, sharing research findings and making sure that it is also being communicated throughout the broader gem and jewelry marketplace.

Manfred Eickhorst: The Future of LED Lighting in Gemology

LED as a universal "workhorse" for gems and gemology is one of the exciting new discoveries – with a wide range of possibilities – that will have a significant impact on the world of gems. In gemology, the specific advantages of LED will, step by step, replace the incandescent lamp as the light source used for refractometers, spectroscopes and darkfield microscopic illumination. And this is just the beginning of the important applications of LED lighting in the 21st century.

Brendan Laurs, James Riley & Ya'akov Almor - An update on the Journal of Gemmology


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