"MINERAL: beryl
CHEMISTRY: Be3Al2Si6O18
COLOR: greenish blue, light in tone
REFRACTIVE INDEX: 1.577 to 1.583
BIREFRINGENCE: 0.005 to 0.009
SPECIFIC GRAVITY: 2.72
MOHS HARDNESS: 7.5 to 8.0

Aquamarine’s name comes from the Latin for seawater and it was said to calm waves and keep sailors safe at sea. March’s birthstone was also thought to enhance the happiness of marriages. The best gems combine high clarity with limpid transparency and blue to slightly greenish blue hues. Like many beryls, aquamarine forms large crystals suitable for sizable fashioned gems and carvings."
Source: https://www.gia.edu/aquamarine#gem-overview