Emeralds are gem-quality specimens of the beryl mineral family with a rich, distinctly green color. They are found in igneous, metamorphic, and sedimentary rocks in a small number of locations worldwide.
For over 5000 years, emeralds have been one of the most desirable and valuable colored stones. Ancient civilizations in Africa, Asia, and South America independently discovered emeralds and made them a gemstone of the highest esteem. In the United States and many other countries, emerald serves as the birthstone for people who were born in the month of May.
Today emeralds, together with ruby and sapphire, form the “big three” of colored stones. The “big three” generate more economic activity than all other colored stones combined. In 2015 the value of emeralds imported into the United States exceeded the value of all colored stones outside of the “big three” combined.Emerald is a gemstone and a variety of the mineral beryl colored green by trace amounts of chromium or sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness is classified as generally poor. Emerald is a cyclosilicate.