What Is Aquamarine? A Close Cousin of Emerald

Aquamarine is a blue-to-green variety of beryl — the same mineral species as emerald. The difference between the two comes down to which trace element does the coloring: emerald gets its green from chromium or vanadium, while aquamarine's blue comes from iron.

Most aquamarine on the market has been heat-treated, a stable and widely accepted process that removes a yellowish or greenish undertone from the rough stone, shifting it toward a purer blue. Once treated, the color change is permanent and undetectable without specialized lab equipment. Major sources include Brazil, Nigeria and Madagascar, and it's the traditional birthstone for March.