The Swiss Gemmological Institute (SSEF) has issued an urgent trade alert warning gemstone buyers about a growing fraudulent practice: emeralds being artificially clarity-enhanced after they have received independent laboratory certification.

By treating the gemstones after testing, fraudulent actors are able to falsely inflate the apparent value of the stones while still using the original, clean lab report.

Because the high-end gemstone market heavily favors emeralds with no or minimal clarity modification, some sellers are exploiting the certification process through a multi-step deception:

• Chemical Cleaning: Emeralds previously treated with artificial resins are chemically cleaned with strong solvents to remove the fillers.

• Laboratory Testing: These cleaned emeralds—which may now display prominent, open fissures—are submitted to gem labs for testing. The resulting lab reports accurately state that no or only minor clarity modification was evident at the time of testing.

• Post-Test Treatment: After receiving the clean report, the stones are treated again with oils, resins, or wax to improve their appearance before being sold alongside the outdated certificate.

While filling fissures in emeralds with oil, wax, or artificial resin to improve clarity is a legal and standard practice in the industry, it is a strict requirement that all such treatments be fully disclosed to the buyer.

SSEF warns the trade that this post-certification alteration is on the rise and cautions buyers to remain highly vigilant when purchasing high-value emeralds. The institute noted that the same fraudulent practice is also being observed among other gemstone categories.