The enhancement degree is the amount of filler a lab finds in a gem's fissures: minor, moderate or significant.
In more detail
LMHC wording codes it F1, F2 and F3 for fissures, and C1 to C3 for filled cavities. Lead-glass filling in corundum uses the same F1 to F3 scale. The degree describes the stone at the time of examination, because fillers can change later.
On a grading report
For example: 'indications of moderate clarity enhancement/modification', or F2.
Related terms
- Clarity enhancement: Clarity enhancement is filling surface-reaching fissures with a filler such as oil, resin, wax or glass, so they show less.
- Emerald oiling: Emerald oiling is filling an emerald's fissures with a colorless oil to make them less visible.
- Lead-glass filling: Lead-glass filling is a treatment that fills fissures and cavities in corundum, mostly ruby, with high-lead glass to hide them.
- Resin filling: Resin filling is filling a gem's fissures or cavities with a resin, often one that hardens, to hide them.