@xavier_exelle: 99% of emeralds are oil-treated. That is not a problem. What matters is how. Cedar oil only, no resin, and the level must stay at minor or below. The more oil an emerald needs, the more cracks it has to hide. No oil, insignificant, minor: those are the acceptable tiers. Moderate and above means too many fractures. High jewelry will not touch it, and neither should a serious investor. The full framework is in the latest Gemstone Secrets episode. Link in bio.