Fall 2015 Gems & Gemology: Colombia’s One-of-a-Kind Trapiche Emeralds
HPHT-grown synthetic diamonds, Lesotho’s renaissance, and white nephrite origin study
CARLSBAD, Calif. – Dec. 1, 2015 – The Fall 2015 issue of Gems & Gemology (G&G), GIA’s quarterly professional journal, offers a comprehensive look at a stone that intrigues many gemologists – Colombia’s one-of-a-kind trapiche emerald. The issue, which is now available in print and online, also investigates recent breakthroughs in colorless to near-colorless HPHT-grown synthetic diamonds, how Lesotho’s Letšeng-la-Terae diamond mine became one of the world’s richest, and the provenance of dolomite-related white nephrite jade using a new method of statistical analysis.G&G’s cover story “Colombian Trapiche Emeralds: Recent Advances in Understanding Their Formation” presents a comprehensive paper on the unique trapiche emeralds from Colombia. In fine specimens, the combination of rich, gemmy green color with the six-spoke pattern is particularly striking. The article, headed by UCLA postdoctoral researcher Isabella Pignatelli and Gaston Giuliani, director of the French Institute of Research for Development, reviews the geology of trapiche emerald, provides 3-D petrographic examination of crystals along with spectroscopic and chemical analyses, and proposes a new formation model informed by their recent work.
Next, a team led by GIA research scientist Ulrika D’Haenens-Johansson investigates the gemological properties of 44 colorless to near-colorless HPHT-grown synthetic diamonds recently produced by a Russian firm, New Diamond Technology. Ranging up to 5.11 ct, these HPHT synthetics show dramatic improvement in size, color, and clarity. The issue’s third article, by GIA’s Russell Shor and Robert Weldon and three leading diamond researchers, profiles the Letšeng mine in Lesotho to explain how the operations have been adapted to promote recovery of the mine’s biggest diamonds and increase profitability. In the fourth and final paper, Zemin Luo, Mingxing Yang and Andy Shen from the China University of Geosciences in Wuhan apply a new statistical analysis method to the provenance of dolomite-related white nephrite. This technique could prove useful in accurately determining the geographic origin of other gemstones.
The issue also features G&G’s regular Lab Notes and Gem News International sections, which include informative entries from contributors around the world. The second installment of the G&G Micro-World column features descriptions and photomicrographs of remarkable inclusions.
G&G’s free archive containing every issue from 1934 to present, more in-depth coverage, hundreds of additional photos, and exclusive video footage are available on GIA’s website at http://www.gia.edu/gems-gemology.
