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GIA Examines 35ct. Lab-Grown Diamond

May 7, 2023  |  Anthony DeMarco

The Gemological Institute of America (GIA) has evaluated a 34.59-carat chemical vapor deposition (CVD) diamond — more than double the size of any lab-grown it examined previously.

The emerald-cut, G-color, VS2 stone, which the institute tested in its Hong Kong lab, was produced by Ethereal Green Diamond in India. The gem exhibited qualities consistent with a CVD, type IIa diamond, the GIA said Thursday in an online research note published by its quarterly report, Gems & Gemology.

The institute found small black graphite inclusions in the stone. Some were independently located within the diamond, while others created cloud clusters between growth layers. Weak oily or wavy graining was observed through the table facet when using a microscope, a feature sometimes noticed in CVD diamonds. In addition, lab gemologists found no absorption related to nitrogen, which is consistent with type IIa diamonds.

Previously, the largest CVD lab-grown examined by GIA weighed 16.41 carats, in 2022.

“This more than twofold increase in size within one year is an impressive technical achievement in CVD diamond growth,” said Tom Moses, GIA executive vice president and chief laboratory and research officer. “With such production improvements, correct identification and disclosure are critical to maintaining consumer trust.”

Image: The 34.59-carat lab-grown diamond. (Gemological Institute of America)


GIA Examines 35ct. Lab-Grown Diamond

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