Aquamarine is a variety of beryl, found in stunning sky or sea blue. Its name is from the Latin aqua (water) and mare (sea). The blue colour is due to traces of iron in the crystal structure of beryl.
Aquamarine is closely related to emerald, probably the most well-known member of the beryl family. (Beryl is frequently confused with chrysoberyl, but the two are in fact distinct).
In the Middle Ages, it was widely believed that aquamarine could overcome the effects of poison. The lower body of sirens (mermaids), who could lure sailors to their deaths, was thought to be made of aquamarine, and for this reason sailors slept with aquamarine crystals under their pillows to ward them off, ensuring a safe passage and sound sleep.
The finest aquamarine is found in Brazil. It is also found in India, Russia (Ural mountains), Nigeria, Pakistan and various parts of the USA, including New Hampshire, North Carolina, Colorado and Vermont.