Emerald

Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5-8 on the Mohs scale. Other beryls include aquamarine, heliodor, morganite, and colorless goshenite. Most emeralds are highly included, so their toughness (resistance to breakage) is generally poor. Emeralds are frequently oiled in order to fill in surface reaching cracks which improves their clarity and stability. In grading emeralds, crystal is considered a close second to color. A fine emerald must possess a pure verdant green hue, and a high degree of transparency to be considered a top gem. Fine emeralds must be medium to dark, or 75% in tone. The hue should be bright green. Colombia is the world’s largest producer of emeralds, Zambia being the second biggest producer. But emeralds are found all over the world including several states in the US.  Emerald is the birthstone for May.