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Update on the Identification of Dye Treatment in Yellow or “Golden” Cultured Pearls
Dye treatments in yellow or “golden” cultured pearls have improved to the point that some samples show little surface evidence.
GIA’S Symmetry Grading Boundaries for Round Brilliant Cut Diamonds
A presentation of parameters used to support GIA's symmetry grading system.
Identification of Extraterrestrial Peridot by Trace Elements
Twenty-six peridot samples from the Esquel pallasite meteorite and 27 samples from 10 terrestrial sources were studied by laser ablation.
Dyed Purple Hydrophane Opal
Opals with an unusual purple bodycolor and strong play-of-color have recently appeared in the market.
Special Report on Red Feldspar
A compilation of ongoing research into red feldspar and its sources around the world, as well as the detection of various color treatment processes.
Research on Gem Feldspar from the Shigatse Region of Tibet
The existence of a natural red andesine deposit in China/Tibet has been the subject of controversy since 2006.
The Chinese Red Feldspar Controversy: Chronology of Research Through July 2009
Red copper-containing plagioclase feldspar from Oregon has been available for over a century.
GIAでデビューした素晴らしい宝石彫刻
The display of Perry Brent Davis’s carvings of agate and gem quartz at GIA’s Carlsbad campus looks like a colorful seascape of otherworldly designs.
UV-Vis-NIR Reflectance Spectroscopy of Natural-Color Saltwater Cultured Pearls from Pinctada Margaritifera
Natural-color saltwater cultured pearls from Pinctada margaritifera were studied by diffuse reflectance UV-Vis-NIR spectroscopy.
A Microstructural Study of Pietersite from Namibia and China
Pietersite has been described as a brecciated variety of tiger’s-eye.
An Imitation "Melo Pearl"
A 52.49 carat near-round “pearl” is submitted to the Bangkok laboratory as a “Melo pearl.”
Synthetic Gem Materials in the 2000s: a Decade in Review
An examination of synthetics in the marketplace over the first decade of the 2000s.