Emerald is a green variety of the mineral Beryl. There are many green Beryls but the Emerald variety is characterized by its “Pure Green” which is considered the best color. The GIA considers Emerald to be “vivid, slightly bluish green”.
Major sources of Emerald are Columbia, Zambia, Brazil, and Afghanistan. The best Emerald comes from Brazil with some very nice Emerald coming into the market from Zambia. Brazil produces the largest amount of Emerald for the market but its quality is considered the be third best. The material coming from Afghanistan is promising with regard to quality but the lack of political stability in the area and the ongoing war have seriously curtailed its production. Geographic origin must be determined by an expert and is actually considered the be unreliable. If an Emerald is considered to be valuable enough we may, with the customers permission, send it to the GIA for their lab to give a determination as to region of origin but even the GIA will tell you that their origin findings are not 100% correct.
Zambian Emerald is known for its higher clarity but in larger sizes tends to be too dark although Emerald from this region tends to be more affordable. Columbian Emeralds still represent the highest quality and are the most expensive. For this reason, some suppliers label Emeralds as Columbian which are not, to make them more saleable.
As with almost all colored stones, Emerald is frequently treated for clarity and color. The Emerald is considered a Type III gem which means it usually occurs in a highly included state. The inclusions include fissures and other imperfections which allow access to the interior of the crystal for coloring and stabilizing agents. The treatments are generally permanent with the exception of oils but value may be reduced if the treatments are excessive. Imperfections are used to determine origin and can be very distinctive of their area of the world but treatments can be very difficult to detect if they are carefully done. In the last few decades, polymers have been used to enhance stability and have been combined with coloring agents. The use of polymers and dye should be disclosed and has an effect on pricing. Since the mid 2000’s polymers have been used (usually with dye) to fuse small pieces of beryl or poor quality Emerald to make bigger pieces. These stones are based as low quality and should be disclosed as their value is much lower than untreated material. Prices for untreated, good quality Emerald can be very high and they are also very rare.
As Gemologists we are able to detect some treatments and value your Emerald jewelry. If you have what we consider to be a very valuable Emerald we may recommend that you send it to the GIA LABS for a quality and origin report.
In the future I will be writing more about the various forms of treatments to colored stones…keep checking and thanks for your continued interest….