Aquamarine
(ak'-wa-ma-ren)
16th c.; lat. aqua marina "sea water"
Transparent gemstone of the beryl family with a blue to bluish-green color
Color
Very light to medium dark blue to greenish blue
Chemical composition
Be3Al2(SiO3)6
Hardness (Mohs scale)
7,5 - 8
Specific gravity
2,76 ±0,05
Refractive index
1,577 - 1,583 ±0,017
Birefringence
0,005 to 0,009
Optical character
Uniaxial -