A Chinese lab grown company has produced the largest ever polished diamond by the newer chemical vapor deposition (CVD) method, says GIA.

The 16.41-carat princess-cut gem (G/VVS2) was produced by Shanghai Zhengshi Technology.

Detailed spectroscopic readings confirmed there was no post-growth treatment to improve the color.

It broke a record held by an emerald 14.60-carat diamond (F/VS2) produced by Ethereal Green Diamond, in Mumbai, India, and certified last year by the International Gemological Institute (IGI).

Shanghai Zhengshi Technology held the record before that, with a a 12.75-carat F/VVS2.

The GIA says that as demand for lab growns increases, records for crystal size and quality are frequently broken.

"The first CVD diamond I examined in 2003 was a 0.23 ct pear shape, with clear brown color," said Dr. Wuyi Wang, GIA vice president of research and development, who examined the new record-sized CVD diamond.

"This 16.41 ct laboratory-grown diamond demonstrates the advances in CVD growth technology. This achievement has important implications for the many scientific and industrial applications for high-quality laboratory-grown diamonds."

Chemical vapor deposition (CVD) is a newer method of producing lab-grown diamonds. It does not require high pressures like the longer-established HPHT (high pressure, high temperature) process.