DIAMOND buyers in Shenzhen are advised to be cautious and keep their receipts and quality inspection certificates to avoid being cheated by sellers of synthetic diamonds, also known as chemical vapor deposition (CVD) diamonds, Shenzhen Gold & Jewelry Industry Association said.

    CVD is a chemical process used to produce high-purity, high-performance solid materials. CVD diamonds show mechanical, tribological and even electronic properties comparable to those of natural diamonds and can’t be distinguished with naked eyes, or even with devices.

    The association said the China National Jewelry and Jade Quality Supervision and Inspection Center found more than 200 CVD diamonds during regular sample checks in May and June. Most of the synthetic diamonds were 0.30 carats. Enterprises that sent samples for tests didn’t know they were submitting synthetic diamonds, the center said.

    The association said most synthetic diamonds are sold in Shenzhen and are popular among consumers because of their weight. A survey by the industry association showed most consumers favored diamonds between 0.3-0.5 carats.

    “Shenzhen authorities found dozens of synthetic diamonds last year and the cases kept rising this year,” said an employee at the Shenzhen laboratory affiliated with the national center, according to yesterday’s Daily Sunshine.

    The laboratory has issued warnings to enterprises twice found to be selling synthetic diamonds. Such enterprises will be blacklisted if they’re caught a third time. CVD diamonds are mainly from Hong Kong and purchased from suppliers by mainland businessmen who are told they’re buying natural diamonds. Synthetic diamond prices are generally 20 to 50 percent lower than prices of natural diamonds.

    (Han Ximin)