tanzanite
Photo courtesy of Scott Papper, GIA GG, AJP, Global Gemology & Appraisals
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Variety: Tanzanite
Species: Zoisite Mohs Hardness: 6 to 6.5 out of 10 Color: Light to medium-dark bluish purple and violetish blue to violet. RI: 1.691 to 1.700 (+/-0.005) Birefringence: 0.008 to 0.013 SR/DR/AGG: DR Optic Character: Biaxial positive Pleochroism: Strong. Usually strong blue, purplish red and greenish yellow. Sometimes, strong blue, violet and colorless. Spectrum: Not diagnostic, but you might see bands at 595, 528 and 455nm. Fluorescence: Generally inert SG: 3.35 (+0.10 / -0.25) |
