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GIA Spots CVD Stone in Parcel of Treated Melee
Feb 10, 2019 7:17 AM
By Rapaport News
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RAPAPORT... In a rare case, the Gemological Institute of America (GIA)
has discovered an irradiated chemical vapor deposition (CVD) diamond in a batch of natural melee a
client had submitted for testing.
The GIA’s Tokyo laboratory found the 0.007-carat, irradiated
green-blue synthetic diamond in a parcel of 300 similarly
colored irradiated stones, it said in a recent journal article. The other 299
diamonds were natural, but had too been exposed to an artificial source of
radiation to improve their color. All 300 stones were round, with the parcel
weighing a total of 1.97 carats.
“Irradiated CVD synthetic diamonds are rarely seen at GIA,
which had examined only six of them before this report,” Shoko Odake, a
research scientist at the GIA in Tokyo, wrote in the Winter 2018 edition of the
institute’s quarterly journal, Gems & Gemology. “Previously reported
irradiated CVD synthetic diamonds were relatively large, from 0.43 to 1.34
carats. This is the first melee-sized irradiated CVD synthetic diamond examined
by GIA.”
The GIA often identifies synthetic melee mixed in with
natural diamonds, though most cases involve colorless stones. In the Winter
2014 issue of Gems & Gemology, researchers in New York revealed they
had found 14 High Pressure-High Temperature (HPHT) synthetics and one
HPHT-treated natural diamond in a parcel of 359 yellow melee diamonds.
Image: The 300 green-blue diamonds the GIA screened, with the CVD stone on the far right. (Shunsuke Nagai/GIA)
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Tags:
chemical vapor deposition, cvd, Gemological Institute of America, gems & gemology, GIA, High Pressure-High Temperature, HPHT, irradiation, melee, Rapaport News, Shoko Odake, Synthetic diamonds, Synthetics, tokyo, treated, treatment
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