Gemmological Science International (GSI), a global leader in diamond and jewellery certification, 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.
"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," says Debbie Azar, President, and Co-Founder of GSI.
“The challenge arises as most jewellery screening equipment in the market is designed to screen white near-colourless diamonds” , Azar adds. 
GSI utilizes a proprietary process for screening and detection of finished diamond jewellery. This process includes distinctive knowledge and expertise, advanced equipment and most recently AI enabled equipment all of which enabled us to detect these 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 1ct.
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. 
GSI continues to stress the importance of using proper processes, equipment and expertise when identifying diamonds.
The advancing technology in diamond growth is contributing to increased success by growers to replicate natural diamonds more and more. GSI remains a global leader in testing and detecting undisclosed lab-grown diamonds in finished jewellery, ensuring the integrity of the industry. Currently, GSI is the only major laboratory that offers screening and detection for finished diamond jewellery globally and at scale- screening millions of diamonds each year.