Nearly all emeralds have undergone some sort of clarity enhancement to improve their appearance. The type of treatment, and to what extent, determines the overall quality and value of the emerald.
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Photo courtesy of Gem Society
Nearly all emeralds have undergone routine oil treatment, filling their surface-reaching fissures and improving their overall appearance.
According to the LMHC (Lapidary Manual Harmonisation Committee), there are 5 categories of oil treatment:
1. NO SURFACE REACHING FISSURES PRESENT Very rarely will an emerald have zero surface-reaching fissures.
2. NO OIL / INSIGNIFICANT No oil emeralds have not undergone treatment. Emeralds with insignificant grades can also technically be untreated, but are given thedesignation if treatment of tiny fissures is possible.
3. MINOR Only a small amount of oil is required to fill 1 or 2 surface-reaching fissures.
4. MODERATE Multiple surface-reaching fissures, 1 or more of which runs across the table.
5. SIGNIFICANT Many surface-reaching fissures that could potentially pose a durability issue.
Fracture-Filled / Dyed
Photo courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA)
Emeralds with large, surface-reaching fractures or cavities are sometimes filled with synthetic polymers to improve their appearance.
These synthetic filler materials can be transparent or dyed green to improve the emerald's color.
Fracture-filled emeralds are worth considerably less than emeralds that have only undergone oil treatments. Dyed emeralds are worth even less.
Look for blue or orange flash effect to indicate fracture-filled clarity enhancement.
All photos courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA)