GIA Discovers New Mineral, Crowningshieldite

The Gemological Institute of America (GIA) has discovered a new mineral, which has been named crowningshieldite in honor of the late GIA researcher G. Robert Crowningshield, it announced at its International Gemological Symposium on Oct. 8.

Crowningshieldite was first discovered in two diamonds from the Letseng mine in Lesotho. It was accepted as a new mineral by the International Mineralogical Association on Sept. 5.

The two Lestseng diamonds that contained the mineral were both CLIPPIR diamonds—a kind of type IIa gem that forms at significantly greater depths than most diamonds.  (CLIPPIR stands for Cullinan-like, Large, Inclusion-Poor, Pure, Irregular, and Resorbed.)

Crowningshieldite has a hexagonal structure and is believed to be an altered form of the iron and nickel metallic inclusions commonly found in CLIPPIR diamonds.

A specimen of the new mineral will be housed in GIA’s museum collection at the GIA’s Carlsbad, Calif., headquarters.

Crowningshield, a onetime GIA vice president and cofounder of its lab, has been credited with many important gemological discoveries. In 1956, he discovered and documented the spectroscopic feature that characterizes yellow irradiated diamonds. In 1971, he wrote the first report on gem-quality, laboratory-grown diamonds, discovering certain features—like color zoning, metallic inclusions, and uneven patterns of UV fluorescence—that are still used today for identifying lab-created gems.

He also made several important discoveries and contributions about pearls and colored stones, including a landmark 1993 article that laid out a naming convention for orange-pink “padparadscha” sapphire. He died in 2007.

“Discoveries such as this propel our understanding of diamonds and the earth forward,” said Tom Moses, GIA executive vice president and chief laboratory and research officer, in a statement. “I can think of no better way to honor Mr. Crowningshield’s legacy.”

Top: Photo of a diamond that includes the newly recognized mineral crowningshieldite, in the dark area circled in red (photo courtesy of Gemological Institute of America; photo by: Dr. Evan Smith).

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