Aquamarine
Aquamarine is the blue to blue-green variety of beryl. It's name comes from the resemblance it has to seawater in color and legend has it that wearing aquamarine ensures a long and happy marriage. Since treatment of this gem does not intensify or add color, dark colored aquamarine is very rare, and not often available. . These gems are found in many parts of the world, but the majority of commercial production occurs in Brazil and East Africa. Aquamarine has a hardness of 7 which makes it suitable for most jewelry.
Treatments: Heating at low temperatures removes the yellow component of color, leaving the stone icy blue.