Emerald (Be3(Al,Cr)2Si6O18) is probably the most important variety of Beryl, a green, hexagonal, precious gem stone. It is a beryllium-aluminium-silicate with a good hardness of 7.5 to 8. Emerald, aquamarine, morganite, heliodor and beryl form the large gemstone family of the beryls. Traces of chromium and vanadium are responsible for the fascinating green colour.
It is found at various locations all over the world, but the majority of gem quality Emeralds come from the area of Muzo, Colombia. Emeralds from Zimbabwe are probably the oldest gemstones of the world, they were formed 2.6 Ga ago. Emeralds from Pakistan are only 9 million years old.