Color is the most important factor in determining value of this gemstone. Ideal color is a unique rare vivid green typically with bluish undertones.
While inclusions in other gemstones may be looked down upon, it is an excepted fact that natural emeralds are usually heavily included. Emeralds are often characterized by a garden of included crystals trapped within and these inclusions are called “jardin”. Under magnification, the inclusions in emeralds resemble foliage; lacy leaves and branches.
Most emeralds are treated to insure stability. Most common is immersion in colorless oil and/or resin to fill minute voids. This is considered common practice.
Emeralds are somewhat fragile and care should be taken in wear and storage to protect them from scratches, sharp blows, household chemicals and extreme temperature change.
Important sources for mining emeralds are in Columbia and Brazil as well as in African countries of Tanzania, Zambia, and Zimbabwe.