IGI recently analyzed a 6.01 carat pear-cut gemstone with a grading report number inscribed on the girdle corresponding to a natural diamond, but concluded that it was a laboratory grown diamond. That lab grown stone’s carat weight, physical spread, and primary qualities were a close match with the natural diamond’s online grading data.
“Everyone in our industry must be vigilant,” stated CEO Tehmasp Printer. “IGI pioneered the grading of lab grown diamonds nearly two decades ago for the purpose of clear separation from natural stones. As attempted fraud increases, the need for ongoing verification is a necessary step to protect consumers from purchasing misrepresented gems and jewelry.”
Subtle Discrepancies: While the main qualities of the stone paralleled the online report data the inscription pointed to, IGI’s gemologists soon deduced that it was lab created. Photoluminescence spectroscopy revealed a doublet at 737 nm due to Silicone Vacancy (SiV) defects, indicating laboratory growth using the Chemical Vapor Deposition (CVD) process.
This was further supported by microscopy, which showed a carbon inclusion in place of the feather indicated online, and a cloud, which would result in a lower clarity grade from IGI. A slight depth mismatch was also revealed. Such discrepancies could go unnoticed outside of a laboratory, particularly once the stone is set into a piece of jewelry.