Emerald oiling is filling an emerald's fissures with a colorless oil to make them less visible.
In more detail
Oil can seep out or dry over time, and steam can make it sweat out. The fissures can then show again, and a jeweler can re-oil the stone. Clean oiled emeralds with warm, soapy water only.
On a grading report
Fissure filling or clarity enhancement, with its degree. Some labs also name the filler as oil.
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.
- Resin filling: Resin filling is filling a gem's fissures or cavities with a resin, often one that hardens, to hide them.
- Emerald: Emerald is the green to bluish green variety of the mineral beryl. Chromium, vanadium or both cause its color.
- Enhancement degree: The enhancement degree is the amount of filler a lab finds in a gem's fissures: minor, moderate or significant.
- Stability: Stability is a gem's resistance to damage from heat, light and chemicals.