The Gem-A editorial team are excited to launch the latest issue of The Journal of Gemmology, Volume 36, No. 2, keeping the Gem-A community updated with the latest in gemmological research.
Features in the Spotlight
Focusing on Blue Zircon from Ratanakiri, Cambodia, authors Manuela Zeug, Lutz Nasdala, Bhuwadol Wanthanachaisaeng, Walter A. Balmer, Fernando Corfu and Manfred Wilder share their recent research exploring the colouration of Ratanakiri zircon, which is well known for its vivid blue colour under heat treatment.
These zircon samples from Ratanakiri (0.3-5.1g) include two untreated brown crystals and three blue specimens that were heat treated at ~1000°C under reducing conditions for a few hours.
Photo by M. Zeug.
The actual cause of Ratanakiri zircon’s colouration is still under debate: while the untreated brown material turns blue under reducing conditions (~900-1000°C) the specimens analysed in this paper demonstrate that the heat treatment does not result in detectable changes in the zircon’s structural state. Here, Zeug et al, offer their data to help address this ongoing debate.
More Feature Articles
In our other feature articles, Shi Tang and his team discuss their analysis of a thick overgrowth of CVD synthetic diamond on a natural diamond that was identified at the Beijing laboratory of the National Gemstone Testing Centre (NGTC) in October 2017.
Distribution of CVD synthetic diamond overgrowth on a natural diamond, discussed by Tang et al.
Elsewhere, Emmanuel Fritsch FGA and Aurélien Delaunay explore the characteristics of Chameleon Diamonds, with an example of an ‘Atypical 25.85 ct Stone’, while SSEF’s Laurent Cartier FGA and Michael Krzemnicki FGA, together with Bertalan Lendvay and Joana Meyer, review the use of DNA fingerprinting on pearls, coral and ivory in gemmology.
Biogenic gem materials suitable for DNA testing include items such as these from the SSEF and H.A. Hänni collections:
cultured pearls and associated shell material (P. maxima and P. margaritifera ~15cm tall), corals (including Corallium rubrum branches up to ~ 10cm tall) and ivory (warthog and mammoth).
Photo by Vito Lanzafame, SSEF.
Stay Updated with Gem Notes
This issue also returns with our regular installments on the latest technology and equipment in our ‘What’s New’ section, together with a round-up of the latest on gemstone analysis in ‘Gem Notes’.
Make sure you don’t this issue’s ‘Conferences’, which features reports on the 15th Annual Sinkankas Symposium on Tanzanite and Tsavorite, and the 76th Swiss Gemmological Society Annual Conference.
READ MORE: Gems and Jewellery Summer 2018 Has Arrived
Gem-A members are kept up-to-date with the latest events and conferences in the gemmological calendar in our ‘Gem-A Notices’ and ‘Learning Opportunities’ section, while ‘New Media’ and ‘Literature of Interest’ keeps you fully informed on the latest gemmological publications.
So, Gem-A members look out for your copies of the Journal of Gemmology Vol 36.2, which are on their way to you now! Alternatively you can log in to access your online copy. ■
Interested in finding out more about gemmology? Sign-up to one of Gem-A’s courses or workshop
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