Aquamarine is the green-blue to blue variety of the mineral beryl. (Emerald is the green to bluish green variety of the same mineral.) Its color is usually a light pastel greenish blue.
This 20.83-carat stone from Africa represents the large size and attractive color that make aquamarine a much-prized gem. - De'ev Dvir/ICA, courtesy Gemstar Ltd., Israel
Heat treatment usually gives it a more bluish appearance.
Aquamarine crystals are known to be large in size and relatively clean and well-formed, making them particularly valuable to collectors of mineral specimens.