GSI detects undisclosed lab-grown diamonds in brown diamond jewelry

amid rising demand for off-color naturals

New York, NY, November 4, 2025 — Gemological Science International (GSI), one of the world’s largest gemological organizations, has identified undisclosed lab-grown diamonds in jewelry set with natural brown diamonds. The discovery comes at a critical time, as the global jewelry trade increasingly promotes off-color natural diamonds, such as brown and champagne hues, as unique, fashionable, and affordable alternatives to traditional colorless stones.

Using advanced instrumentation, including Fourier Transform Infrared Spectroscopy (FTIR), DiamondView imaging, and Raman spectroscopy with liquid nitrogen cooling, GSI gemologists confirmed that several jewelry items contained lab-grown diamonds mixed alongside natural brown stones. The detected colors ranged from near colorless with faint brown modifiers to fancy dark brown.

This finding builds on GSI’s earlier research into colored lab-grown diamonds, which demonstrated that synthetics can mimic a broad spectrum of natural hues. Together, these results highlight the importance of rigorous screening protocols and transparent disclosure practices to protect both industry stakeholders and consumers.

“As the industry embraces natural brown diamonds, it is essential to safeguard their integrity in the marketplace,” said Debbie Azar, President and Co-Founder of GSI. “Our mission is to ensure consumer confidence by applying advanced science to protect retailers, manufacturers, and the trade — and to support the industry’s efforts to promote natural off-color diamonds with trust and transparency.”

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To learn more about GSI’s services, education programs, or color stone capabilities, visit

www.gemscience.net.

About GSI:

Gemological Science International (GSI) is the only major gemological organization established in the 21st century. Founded in 2005 in New York City, it has grown to become one of the largest gemological entities in the world with laboratory facilities spanning four continents. Utilizing cutting-edge processes and proprietary technologies, along with a commitment to the highest ethical standards and practices, GSI provides manufacturers and retailers globally with a wide range of gemstone identification and grading services. The company is committed to advancing gemological research and offers gemological educational programs for trade professionals and the general public through its state-of-the-art research center.