How We Grade

Nearly every emerald on earth has been oiled. That is normal and accepted — hiding it is not. US sellers are required to disclose clarity enhancement, and most of the trade does it quietly, in the footnotes. We put it in the product title.

Stage	What happens
01 — Bought in Bogotá	Purchased against an export invoice from registered sellers, never cash across a table.
02 — Graded before listing	Weight, dimensions, colour and oil grade recorded in daylight-balanced light, with the loupe photo taken the same day.
03 — Reported over 1 carat	Stones above 1.00 ct ship with an independent laboratory report naming origin and enhancement.
04 — Returnable for 14 days	If an independent lab grades a stone lower than we did, the return ships at our cost.

Questions buyers actually ask

Straight answers about oil, origin and certification — the three things that decide what an emerald is worth. If a seller will not answer these, that is your answer.

Are Colombian emeralds treated?

Almost all of them are. Emeralds form with natural fissures reaching the surface, and the trade has filled those fissures with cedar oil for centuries to make them less visible. Treatment is normal and accepted. Failing to disclose it is not.

What does “minor oil” mean on an emerald?

It is a grade of clarity enhancement. Laboratories use a scale — none, insignificant, minor, moderate, significant — describing how much filler sits in the stone’s fissures. Minor means a small amount, visible under magnification but not obvious to the eye.

Does oil make an emerald worth less?

At the same colour, clarity and size, less oil means more value. An untreated Colombian emerald of good colour is genuinely rare and prices accordingly. A heavily oiled stone is not fake — it is simply worth less, and it should cost less.

Can the oil come out of an emerald?

Yes. Ultrasonic cleaners, steam, heat and solvents can strip the filler, and the fissures then become more visible than when you bought the stone. This is why an oiled emerald should never go in an ultrasonic cleaner, and why a closed bezel protects one better than an open setting.

Do I need a laboratory report?

For anything over roughly one carat, yes. A report from an independent laboratory such as GIA or AGL names the origin and the degree of clarity enhancement — the two facts that set the price. Without them you are trusting the seller’s word on both.

How do I tell a real emerald from glass or a synthetic?

Natural emeralds carry irregular inclusions and uneven colour zoning. Glass-filled stones show flash effects along the fractures when you rock them under light, and lab-grown emeralds are often suspiciously clean for the price. A loupe narrows it down; only a laboratory is definitive.

Which Colombian mine produces the best emeralds?

Muzo is the historic benchmark for warm, saturated green. Chivor tends bluish. Coscuez runs lighter and more included, and La Pita has produced fine material since the 1990s. Mine name is a quality signal, not a guarantee — a poor Muzo stone is worse than a fine Coscuez one.