The Swiss Gemmological Institute (SSEF) has issued a trade alert warning the coloured gemstone industry about a fraudulent practice involving emeralds that are re-filled after laboratory examination and subsequently sold using reports that no longer reflect their actual condition.
According to SSEF, the practice involves emeralds that have previously undergone clarity enhancement with fillers such as oil, wax or artificial resin. In some cases, these fillers are chemically removed before the stones are submitted to a gemmological laboratory for testing. As a result, the laboratory may issue a report indicating “no” or “minor” clarity modification based on the stone’s condition at the time of examination.
The institute has identified instances where the same emeralds are later re-filled after certification and marketed using the original laboratory report. SSEF said this creates a misleading impression for buyers because the report no longer corresponds to the gemstone’s treatment status.
The laboratory noted that disclosure of clarity enhancement is required under Laboratory Manual Harmonization Committee (LMHC) guidelines, as the presence and extent of fillers can have a direct impact on an emerald’s value. It added that increased demand for minimally treated or untreated emeralds has created incentives for such practices in the high-end market.
SSEF emphasized that its reports describe a gemstone only as it existed at the time of testing and do not guarantee that the stone has remained unchanged thereafter. The institute also stated that when filler substances are detected, it identifies both the extent of clarity modification and the type of filler, including oil, artificial resin or wax.
To reduce the risk of misrepresentation, SSEF has advised buyers and traders to verify the authenticity of laboratory reports and consider re-testing fissured emeralds before completing transactions, particularly when reports are not recent. It also recommended exercising caution when an apparently clean emerald is accompanied by documentation indicating no clarity modification.
The institute further noted that similar concerns may apply to other fissure-bearing gemstones and urged continued vigilance across the coloured gemstone supply chain.
