Gemological Science International (GSI) has raised a red flag over a notable increase in undisclosed laboratory-grown brown, yellow, and pink diamonds infiltrating natural diamond jewellery and posing as natural diamonds.

Debbie Azar, President, and Co-Founder of GSI, said, “Over the past several months, our team has seen a rise in laboratory-grown coloured diamonds, primarily in brown, yellow, and pink, being mixed in with natural-coloured diamonds in jewellery. The challenge arises as most jewellery screening equipment in the market is designed to screen white near-colourless diamonds.”

GSI said its proprietary process and AI-enabled equipment enables it to detect undisclosed laboratory grown coloured diamonds.

Many of the undisclosed laboratory-grown coloured diamonds detected by GSI were Type IIA   with a single nitrogen. All were mounted in jewellery and vary in size, ranging from melee and as large as 1 carat.

In some instances, the undisclosed lab-grown coloured diamonds were intentionally cut to mimic natural diamonds. Severe fractures, pinpoint clouds, and polished-over “naturals” were observed, including distinct brown grain lines. These features closely resemble those found in natural diamonds, potentially passing standard gemmological observation.