GIA Sees Largest CVD Lab-Grown: 34.59 Carats
By Rob Bates | May 05, 2023
"The GIA laboratory in Hong Kong recently examined the largest lab-grown diamond produced by the chemical vapor deposition (CVD) method it had ever encountered.
GIA graded the 34.59 ct. emerald-cut diamond as G color, VS2 clarity. It was produced by Ethereal Green Diamond in India, and measures 24.94 x 13.95 x 9.39 mm.
Prior to this, the largest CVD diamond GIA had ever seen was a 16.41 carater in 2022. The new one is 111% larger.
“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, in a statement.
Researchers found small black graphite inclusions in the stone—some were along the inside of the body, while others formed clusters of clouds between growth layers. Microscopic observation showed a weak “oily” or wavy graining look on the table, which is sometimes seen in CVD diamonds.
It was also annealed with high-pressure, high-temperature (HPHT) treatment. GIA published more technical information on the diamond in its journal Gems & Gemology.
Generally, the HPHT production method has produced bigger diamonds than chemical vapor deposition. In February 2022, the International Gemological Institute said it had examined a 150 ct. piece of HPHT-grown rough. ... "
https://www.jckonline.com/editorial-art ... own-34-59/