Oil-free emerald is the true rarity
Virtually every emerald on the market has been treated with oil or resin to reduce the visibility of surface-reaching fissures. The practice is centuries old and openly disclosed, but it means a stone certified with no clarity enhancement is genuinely uncommon. No-oil certification adds 50-100% over minor-oil pricing on comparable material, and a stone graded significant oil may be worth a third of its minor-oil twin.
Colombian material from Muzo and Chivor sets the reference for colour, a saturated bluish green that the Zambian and Brazilian deposits approach but rarely equal, and commands a 30-50% premium over them. In 2026 a top-tier no-oil Colombian stone at two carats exceeds $25,000 per carat, while commercial heavily-oiled material trades between $400 and $1,500.
Because emerald is an included stone by nature, buyers accustomed to diamond clarity standards misjudge it. The trade grades emerald on colour first. An untreated stone with fine colour and acceptable clarity is the material that holds value across decades.
