The Swiss Gemmological Institute (SSEF) has issued a trade alert warning of a growing fraud in the emerald market involving gemstones that are re-treated after laboratory testing and sold with certificates that no longer reflect their actual condition.
According to SSEF, some emeralds are stripped of fillers such as oil, wax or resin before being submitted for laboratory examination. The stones may then receive reports indicating “no” or “minor” clarity modification. After certification, however, the gemstones are re-filled and marketed using the original reports, potentially misleading buyers.
Growing concern
The institute said rising demand for untreated or minimally treated emeralds has increased incentives for such practices, as these stones command significant price premiums in the market.
While clarity enhancement is widely accepted in emeralds, international LMHC guidelines require disclosure of both the presence of fillers and the extent of treatment because they have a direct impact on value.
SSEF emphasised that laboratory reports reflect the condition of a gemstone only at the time of examination. Any subsequent cleaning, filling or modification can render the report outdated.
Industry advisory
To protect buyers and traders, SSEF has recommended re-testing fissured emeralds before purchase, particularly when certificates are not recent.
The institute also advised caution when visually clean emeralds are accompanied by reports indicating no clarity modification.
SSEF noted that similar risks exist in other fissure-bearing gemstones, including rubies, and called for greater vigilance across the coloured gemstone trade.