neil cohen, gemologist appraiser, connecticut

 

 

 

 

Indicolite Tourmaline

 

Color: Blue, sometimes with a hint of green


Moh’s Hardness:
7-7.5


Refractive Index: 1.616-1.652


Critical Angle: 38.23°


Specific Gravity: 3.02-3.26


Cleavage: None


Fracture: Uneven, small conchoidal.


Dispersion: Medium (.017)


Heat Sensitivity: Can be delicate and care must be taken when dopping with heat and wax.


Dichroic: Strong (many color variations)


Birefringence (double refraction): Medium (.014-.024)


Crystal structure: Hexagonal

 

Treatments: Generally not treated, but sometimes heated to lighten dark rough.

 

 

 

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