Glossary
Clarity enhancement (F1–F3)
Fissures in emeralds and other stones are often filled with oil or resin to make them less visible. Laboratories state the amount: F1 minor, F2 moderate, F3 significant – or record that no filling is detectable. Minor filling is customary in the emerald trade; the less filling, the more valuable and stable the stone.
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Updated 2026-10-06