Gemological Science International (GSI), one of the world’s leading gemological laboratories, has identified undisclosed lab-grown diamonds in jewellery featuring natural brown diamonds. The finding comes at a time when the global trade is actively promoting brown, champagne, and other off-colour natural diamonds as stylish and attainable alternatives to traditional colourless stones.
GSI gemologists confirmed the presence of lab-grown diamonds using advanced testing methods, including Fourier Transform Infrared Spectroscopy (FTIR), DiamondView imaging, and Raman spectroscopy conducted with liquid nitrogen cooling. The tested jewellery items contained a mix of natural and lab-grown stones ranging from near-colourless with subtle brown modifiers to more saturated, fancy dark brown hues.
This development follows GSI’s earlier research demonstrating how lab-grown diamonds can closely mimic a wide spectrum of natural diamond colours. Together, the findings underscore the need for robust screening processes and clear disclosure practices to preserve consumer trust.
“As the industry embraces the beauty and uniqueness of natural brown diamonds, it becomes increasingly important to safeguard their integrity,” said Debbie Azar, President and Co-Founder of GSI. “Our role is to support the trade with advanced science and ensure retailers and consumers alike can make informed, confident purchases.”
The organization reiterated its recommendation that retailers, manufacturers, and wholesalers maintain strict testing and verification protocols, especially when dealing with large mixed parcels or finished jewellery.
