Oil Filling, Emerald

Fractures look less visible face-up but show flash effects when tilted. Under darkfield, fissures may show yellow, orange, blue, or greenish flashes depending on filler and lighting.

What to look for

Fractures look less visible face-up but show flash effects when tilted. Under darkfield, fissures may show yellow, orange, blue, or greenish flashes depending on filler and lighting.

What it means

Oiling is common in emerald and improves apparent clarity. Degree of filling matters: minor, moderate, or significant treatment affects value.

Expert move

Rotate the stone slowly under darkfield illumination. A flash moving along surface-reaching fractures is the key sign.