Treatments and what “natural” means.
This practice is ancient, near-universal and accepted by the trade, provided it is disclosed. What matters to a buyer is not that a stone has been treated but how much. Independent laboratories describe the degree of clarity enhancement on a simple scale, none, minor, moderate, or significant, based on how much filler a stone carries and how visible its fractures are. That single word does more to place a stone in the market than almost anything else on the report.
An emerald with no enhancement, or only minor enhancement, is considerably rarer and commands a premium for it. Fillers are also impermanent, heat, solvents and ultrasonic cleaning can disturb or remove them, which is why treatment level feeds directly into how a stone must be cared for and why some stones are re-oiled over their lifetime.
