Emeralds have more fractures and inclusions than most other gemstones because they form under very violent geological conditions. Emeralds have long been treated with colorless oils such as linseed oil or cedarwood oil to soften the visible effect of inclusions and fractures.

A practice that is generally not accepted by the trade is that of treating emeralds with epoxy resins such as Opticon. In a process similar to oiling, an emerald's surface-reaching cracks and fissures are filled with epoxy resins.

While colorless oils tend to soften the effect of inclusions, epoxy resins tend to hide the inclusions.

Another practice not accepted is the use of green colored oils to improve color. This treatment is not permanent.

When buying emeralds from a jeweler, always ask for full disclosure on any treatments that have been done and make sure they are listed on the bill of sale.