The Gemmological Association of Great Britain (Gem-A) has launched the latest issue of its flagship scientific publication, The Journal of Gemmology (Volume 39, No. 8, 2025).
Released digitally on December 17, this issue contains news and research from the international gemmological community. Highlights include a feature article that describes the successful applications of unsupervised machine learning algorithms to the geographic origin determination of Cu-bearing tourmaline.
Further feature articles take a closer look at the Imperial Crown of the Holy Roman Empire and its wealth of gemstones and pearls, as well as the limitations of using trace-element signatures for distinguishing the geological and geographic origins of gem corundum.
Editor-in-chief Brendan Laurs FGA, who was recently announced as the recipient of the 2025 Antonio C. Bonanno Award for Excellence in Gemology from the Accredited Gemologists Association (AGA), comments: “This issue closes the year with an important application of machine learning to the origin determination of gem materials, rounding out a trend we’ve been seeing regarding the increased use of artificial intelligence for addressing complex gemmological challenges. The Journal continues to be a valuable resource for keeping track of exciting new developments in the science of gemmology.”
In addition to the feature articles, the Gem Notes section provides numerous brief reports on diverse items of gemmological interest from around the world. Among the many items covered in this issue are an unusual purplish ‘chameleon’ diamond, unheated pink sapphires with conflicting evidence for heat treatment, unusual fluorescence in a Be-diffused ruby, and two reports on interesting non-nacreous natural pearls.
The practical and useful What’s New column highlights recent publications and online resources of interest to gemmologists, while the Learning Opportunities section contains a detailed listing of upcoming conferences and educational events to further the professional development of its readers. Finally, the New Media section compiles information on new gem- and jewellery-related books.
Gem-A CEO Cath Hill adds: “This has been another fantastic year for The Journal of Gemmology, which continues to be a vital resource and respected scientific publication for the international gemmology community. I would like to personally congratulate Brendan Laurs, our esteemed Editor-in-Chief, on securing the 2025 Antonio C. Bonanno Award for Excellence in Gemology. The recipient of this prestigious accolade is chosen by members of the Accredited Gemologists Association (AGA), highlighting Brendan’s impressive reputation and outstanding contribution to the field. I look forward to seeing what 2026 will bring and reading about the latest advances, research and findings in upcoming issues of The Journal.”
A leader in its field, The Journal publishes original research articles on all aspects of gemmology, including natural stones and their treatments, synthetics, and simulated gem materials. It is published quarterly by Gem-A in collaboration with the Swiss Gemmological Institute SSEF.
Issues published in the past two years are accessible to Gem-A Members nationally and internationally. Previous issues are freely available to anyone via The Journal’s online archive. A cumulative index covering all issues from 1947 through 2024, and numerous bibliographies covering specific subjects, can also be freely downloaded from The Journal’s website.
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Anyone can become an Associate Member of Gem-A and receive access to both Gem-A publications: The Journal of Gemmology (print and online) and Gems&Jewellery (online). Visit the Gem-A website to find out more.
Cover: Copper-bearing (Paraíba-type) tourmaline is highly valued in the gem trade, particularly those from Brazil. Distinguishing stones from Brazil, Mozambique and Nigeria can be challenging, and an article on pp. 772–787 describes the use of machine learning to geochemically separate material from these three localities. The stones on the cover are rescaled to similar visual size, and from the upper left, they consist of a 9.3 ct oval from Mozambique, a 5.2 ct cushion from Brazil, a 19.3 ct pear shape from Mozambique, a 60 ct cushion from Nigeria and a ring containing a 4.3 ct oval from Brazil. The matrix specimen of Cu-bearing tourmaline, feldspar and quartz is approximately 8 cm wide and is from Brazil. Images by Luc Phan, SSEF; digitally arranged by Dr Michael S. Krzemnicki. The ring is courtesy of Wilds Company Ltd (Hong Kong).
Unheated Pink Sapphire from Madagascar: A parcel of pink to purplish pink sapphires that was recently mined from Ilakaka, Madagascar. Photo by H. A. O. Wang.
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