Aquamarine is a gemstone, named for its blue-green color, which looks like some shallow seas. It is a type of beryl. The color aquamarine is named for the gemstone.

Color Blue, Very slightly Greenish Blue, Greenish Blue, Very strongly Greenish Blue, or Green-Blue
Mohs scale hardness 7.5 - 8.0
Specific gravity 2.63 - 2.91
Refractive Index 1.567-1.590