Fractures are fairly common in rough emeralds, and as many of these as possible are removed during cutting. Even so, fractures often remain as imperfections that detract from beauty. Because of this, making fractures less visible by filling them with oils that have a similar refractive index to that of emerald is a treatment that has long been used. In recent years, though, this treatment is being used in more extreme cases, and the reappearance of large fractures as the oil evaporates over time is becoming a problem. The use of polymers instead of oils to fill fractures, followed by hardening the polymer at the surface of the fracture, is also becoming common.

Untreated emeralds suffer more weight loss during the cutting process, making them more expensive, but they are valuable because their appearance will remain unchanged as long as they are not struck against something and damaged. Though they may appear the same at a glance, untreated emeralds are much more transparent than treated emeralds, a difference that is apparent even to the unaided eye when several of each type are viewed together.

Dealers often immerse rough emeralds in baby oil to make their insides more easily visible. After inspecting the rough, oil that has penetrated the fractures is removed by ultrasonic cleaning. Other than in this situation, untreated emeralds are never exposed to oils.

When looking at the quality of emeralds and determining whether or not they are treated, it is important to have an understanding of the treatment process. It is possible to determine the degree of impregnation and the filling material used through scientific analysis with magnification and spectrophotometry, but treatment is still possible after such inspection, and the data contained in a laboratory report cannot be considered a guarantee.

Even among gemstones such as diamond, ruby, and aquamarine, low-quality material with numerous fractures may be treated by impregnation with oil or lead glass. When coming across gemstones with especially low prices in spite of ad fine appearance, one should suspect fracture-filling treatment.