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GIA Scientists Evaluate Rare 2.33-Carat Red Diamond, Now on Display at Smithsonian April 14, 2025 (0 comments)
Washington, D.C.--Scientists from the Gemological Institute of America (GIA), in collaboration with the Smithsonian National Museum of Natural History and the Paris School of Mines, have conducted an analysis of the Winston Red diamond. This 2.33-carat stone is described as the fifth-largest diamond with a pure red color known to exist. It is publicly displayed at the Smithsonian National Museum of Natural History.
[Photo by Robert Weldon, courtesy of Ronald Winston, via GlobeNewswire]
According to the GIA's news release, the Winston Red is the only red diamond of its kind currently available for public viewing. Fewer than two dozen pure red diamonds over one carat are known in the public record.
Using advanced instrumentation and historical data, GIA scientists identified the cause of the diamond's red color as plastic deformation—changes to its crystal structure from prolonged exposure to high pressure and heat. The report stated that its mineralogical characteristics suggest an origin in Brazil or Venezuela.
Tom Moses, GIA executive vice president and chief laboratory and research officer, noted he had previously examined the diamond in 1987 and identified its old mine cut and inclusions as consistent with its reported history. GIA attributed the stone's 1938 sale by Jacques Cartier to the Maharaja of Nawanagar.
Dr. Ulrika D'Haenens-Johansson, senior manager of diamond research at GIA, explained in the release that the concentrated red color results from stress-induced structural changes in the crystal. According to GIA, out of more than one million colored diamonds analyzed, only 0.07% were red, and just over half of those received a 'Fancy red' grade, which the Winston Red holds.
The diamond is part of a new exhibit that opened on April 1 at the Smithsonian. Per the release, the display includes 40 additional stones from the Winston Fancy Color Diamond Collection, donated by Ronald Winston, son of jeweler Harry Winston. Dr. Gabriela A. Farfan, curator of gems and minerals at the Smithsonian, stated that this donation is among the most significant additions to the National Gem & Mineral Collection in recent decades.
Learn more in this news release.