The green color of emeralds is unparalleled in the gem kingdom. Its beautiful green color, combined with its rarity, makes emerald one of the world’s most valuable gemstones. Emeralds are a member of the beryl family of minerals. Minute traces of chromium, vanadium and iron give emeralds their famous “green fire.” The green crystals grow slowly within metamorphic rocks and are restricted in size by the host rock, making large emeralds rare and costly.
Unlike other beryl, emeralds often contain inclusions and tiny fractures. These are commonly called jardin, from the French word for “garden,” because of their resemblance to foliage. For emeralds, jardin is not looked on as a negative aspect as it would be for some other gem varieties, but instead is considered part of emerald’s character and can be used to assure the purchaser of a natural gemstone.
Although emerald is relatively hard and durable, it must be protected from harsh blows because the jardin found within make it susceptible to breaking. The famous “emerald cut” was developed specifically for this gem to reduce the amount of pressure exerted during cutting. Transparent emeralds are faceted in gem cuts for jewelry, while translucent material is cut and polished into cabochons and beads. Trapiche emeralds are also cut into cabochons, making exquisite jewelry pieces.
A very small number of emeralds display asterism and chatoyancy; these too are cut into cabochons.
When buying emeralds the most important consideration is always color, with clarity and quality of cut playing second fiddle. Nevertheless, the brightness of the gemstone (which is somewhat determined by the cutting and clarity) is also an important factor.
Traditionally, deep green is the most desired color in emeralds. Paler emeralds are sometimes called green beryl.