Features Garnet Ruby
How they Look?
Chemical Name Silicate Aluminium oxide
Crystal System Isometric Trigonal
Colours Typically red, but can be orange, green, yellow, purple, black, or brown Red
Hardness 6.5 - 7.5 on the Mohs scale 9 on the Mohs scale
Refractive Index 1.72 - 1.94 1.76 - 1.78
Specific Gravity 3.5 - 4.3 4.0 - 4.1
Transparency Transparent to translucent Transparent to opaque
Birefringence None -0.008
Lustre Vitreous to resinous Vitreous
Cleavage None None
Streak White Colourless
Fluorescence Variable Strong - carmine red