Deeply rooted in mineralogy, modern gemology has become increasingly multidisciplinary with the incorporation of theories and techniques from many other scientific branches, especially those in the geoscience realm.
The annual Geological Society of America (GSA) meeting attracts more than 6,000 geoscientists from all over the world and is one of the best platforms for presenting recent research and finding inspiration for future work. Since 2013, GIA researchers have participated in the GSA annual meeting. At the 2015 conference, held in Baltimore Nov. 1–4, GIA hosted two technical sessions, one oral and one poster, with 26 presentations altogether. At the same time, GIA hosted a booth at the exhibition hall in the Baltimore Convention Center, where representatives from the institute were on hand to answer questions.
GEMOLOGY ORAL TECHNICAL SESSION
GIA’s Dr. James E. Shigley and Dr. Wuyi Wang co-hosted the oral session. Dr. George Harlow led with a talk on how gem material studies provide insights on the whole geological system of the Earth. Dr. Wang presented the discovery and distribution of [Si-V]– defects in HPHT synthetic diamonds. This study by a team from GIA’s New York lab challenged the widely accepted theory that [Si-V]– defects only occur in CVD synthetic diamonds, while also showcasing photoluminescence mapping as a powerful research technique.
Taking a truly multidisciplinary approach, Dr. Laurent E. Cartier from the Swiss Gemmological Institute SSEF worked with a biologist to apply DNA analysis to the origin determination of organic gems. The current study is focused on pearls. For the first time, gemologists can conclusively identify the mollusk species of a pearl. Dr. Cartier and his colleagues are working to perfect this technique and exploring the possibilities with other organic gems such as coral and ivory.
Dr. Karen Smit, a postdoctoral researcher from GIA’s New York lab, studied the Re-Os isotope of sulfide inclusions in type Ib diamond from West Africa. The isotopic study was used to explain the assembly of the Gondwana supercontinent. Next, Dr. Steven Shirey from the Carnegie Institution of Washington presented his Re-Os geochronology study on a sulfide inclusion in superdeep diamond from Brazil. The age of this inclusion indicated crystal recycling facilitated by mental convection beneath. Both studies demonstrate the important role gem materials can play in earth science research.
Gemological studies of famous stones and historical jewelry pieces are also of great interest. Alan Hart from the Natural History Museum in London explored the creation of the Mogul cut. Using the famous Koh-i-Noor (”Mountain of Light”) diamond from the British Crown Jewels as a case study, Mr. Hart found that differential hardness was the key factor that brought about the Mogul cut with the primitive cutting tools available at the time. Dr. Raquel Alonso-Perez from Harvard University studied the tourmalines mounted in the Hamlin Necklace, a piece of 19th-century North American jewelry, using both spectroscopic and trace-element analysis.
Inclusion study is one of the pillars of modern gemology. GIA’s leading inclusion researcher, John Koivula, pointed out the possibility of misidentifying synthetic corundum as natural heat-treated material. Experimental studies proved that heat-fused cracks generated in both pulled and flame-fusion synthetic corundum look virtually identical to the features associated with so-called flux-healed natural stones. Dr. Aaron Palke, a postdoctoral researcher from GIA’s Carlsbad lab, found some unusual glassy melt inclusions in sapphires from southwestern Montana. Dr. Palke and colleagues hypothesized that these sapphires crystallized as peritectic minerals during high-grade metamorphism that generated silica-rich melt and an alumina-rich restite. Future research on this topic may shed light on the source and transportation of Montana sapphires.
Phenomenal gems are especially interesting materials for scientific study. Dr. Keal Byrne and colleagues from the Smithsonian Institution investigated the luminesce of “chameleon” diamonds, which show an intriguing color-change response to temperature and/or light. Xiayang Lin from Pennsylvania State University discovered the microscopic surface feature that causes iridescence in natural quartz crystals from India.
Researchers also presented studies on American gem deposits. Dr. Michael Wise from the Smithsonian Institution presented his work on the hydrothermal emerald and hiddenite mined in the Hiddenite area of North Carolina. Yury I. Klyukin from Virginia Tech investigated the fluid evolution of the deposit at North American Emerald Minenear Hiddenite. Dr. William B. Simmons from Maine Mineral and Gem Museum shared the recent discovery of gem-quality pollucite in Mt. Mica pegmatite.
GEMOLOGY POSTER SESSION
The gemology poster session on Nov. 4 featured twelve posters. Although it was held on the final day of the conference, the session was very well attended. The flexibility of presentation time and format allowed for dynamic discussion between exhibitors and viewers.
The posters covered a wide range of topics. GIA researchers displayed their studies on micro-diamonds, diamond defect formation, and low–pressure, high-temperature (LPHT) treatment of type Ia diamonds. Sarah Ostrye presented the GIA library’s rare book digitization project. Catherine McManus of Materialytics introduced her project on diamond origin determination using multivariate analysis of LIBS spectra. Gary S. Michelfelder from Missouri State University and coauthors presented their study on the origin of alluvial diamonds in the Coromandel area of Brazil.
It was also impressive to see Chinese gemology students present their research on newly discovered gem corundum deposit in northeastern China and a color study on tanzanite. Topics and abstracts from the poster session can be found at https://gsa.confex.com/gsa/2015AM/web
In another highlight from the GSA meeting, Dr. Rodney C. Ewing, a professor of geological and environmental sciences at Stanford University, received the Mineralogical Society of America’s Roebling Medal. Dr. Ewing has served on GIA’s board of governors for nine years, providing insightful guidance on research activities and nurturing the institute’s postdoctoral program.
Since their inception at the 2013 GSA meeting, the gemology technical sessions have provided a broader stage to share important research findings with other scientists. The 2016 GSA annual meeting will be held in Denver, and the gemology session organizers will start work on it soon.