9-12-2019
Gemological Science International (GSI) has warned about synthetic diamonds grown using chemical vapor deposition (CVD) could be undergo extreme colour instability.
During testing at its laboratory, a 2-carat CVD diamond was exposed to high powered UV rays and went from near colorless to blue colour. The colour remained after a week and a half. CVD diamond can change colours under UV lights or extreme heat, normally it will return to their normal colour after 30-60 minutes of direct sunlight. Under standard ambient lighting conditions, this particular stone took two and a half hours to return to normal colour.
“It is strongly suggested that all laboratory-grown CVD diamonds are placed in a full-spectrum light box for at least 30 minutes before colour grading,” said Nicolas Del Re GSI chief information officer.
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