Helder Blauwe Aquamarijn ± 0.05 CT. 2.5 mm Rond Color: Bright Blue Clarity: Clean Luster: Fantastic Origin: Africa Hardness: 7.5 - 8 Specific Gravity: 2.67 - 2.84 Refractive Index: 1.57 - 1.60 Chemical Composition: Be3Al2(SiO3)6, Beryllium Aluminum Silicate Crystal Structure: Hexagonal