Almost every Emerald that has ever been pulled from the ground will contain some sort of Fissure or tiny fractures. These inclusions are natural and are part of the Emerald but it is always desirable to reduce the visual impact of these fissures. That is why Emeralds are routinely treated using natural oil which hides the fissures.
LOCALITY- TYPICAL INCLUSION AND FEATURES
Colombia-Three-phase inclusions (liquid-filled cavity containing a crystal and a gas bubble)
India-Two-phase inclusions (liquid-filled cavity containing a gas bubble)
Zimbabwe-Tremolite (usually fibrous or needle-like crystals)
Siberia-Needle-like crystals of actinolite
Many other Localities also has Mica flakes, pyrite and calcite, and also colour zoning.
Single-Phase Inclusion
Single-phase inclusion are rarer than the other two that we will talk about simply because it is not a common feature of Colombian emeralds. Single-phase inclusion can, however, be seen in Musakashi emeralds, which come from an emerald mine of the same name in Zambia. This inclusion looks like a collection of crystals in the stone and is the result of a mineral inclusion, as opposed to a liquid or a gas.
Two-Phase Inclusion
Two-phase inclusion can be found in Colombian emeralds as well as those from other regions. In a two-phase inclusion, we have a gas bubble trapped in liquid, which differs from the single-phase inclusion by not containing a mineral element. These inclusions are often characterised by their jagged appearance.
Three-Phase Inclusion
Three-phase inclusions are like a combination of single- and two-phase inclusions; they are often jagged-edged, and consist of a combination of liquid, gas, bubbles, halite salt (another name for rock salt) and crystals. These inclusions can be described as a pea-pod which is pointed at both ends; the pod is the liquid, gas bubble have formed inside and there is a crystal element also. Three-phase inclusions are especially common in Colombian emeralds - and as Colombia is the foremost emerald exporter in the world, this type of inclusion can be seen in many stones in circulation today.
Other Features
Along with the inclusions being discussed below, the following are examples of what one can expect to see in an emerald:
• Veils - these are small bubble-like inclusions which form a layer which can vary in width and length. In emeralds, these are often formed from liquid and can have a jagged appearance.
• Growth tubes - this inclusion features a series of tubes running parallel to each other.
• Negative crystals - these are distinctive crystal shapes but are actually a cavity in the rock, therefore it is an outline and not a solid substance within the rock.
• Tremolite - this inclusion is very much like that of the growth tubes, except the tubes do not run parallel but rather branch off in different directions.