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Alexandrite
Alexandrite

Bertrandite
Bertrandite



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Alexandrite
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Bertrandite

Alexandrite and Bertrandite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous
Vitreous
1.2 Pleochroism
Not Available
none.
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Transparent to nearly opaque
TransparentAnthony et al, Handbook of mineralogy (2001)
1.5 Refractive Index
1.739-1.7701.583-1.614
Agate Opal
1 3.25
1.6 Optic Character
Biaxial/+
Not Available
1.7 Crystal System
Orthorhombic
Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21
1.8 Birefringence
0.007-0.010Not Available
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentAnthony et al

Alexandrite and Bertrandite Optic Character

Alexandrite and Bertrandite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Alexandrite and Bertrandite Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Alexandrite and Bertrandite optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character. Alexandrite has Biaxial/+ character.

Alexandrite and Bertrandite Transparency

Similar to their colors, Alexandrite and Bertrandite transparency can also be used as criteria for their primary identification. Although transparency cannot be the only criteria for gemstone identification, it can efficiently used in gemstone grading. Talking about their transparency, Alexandrite is Transparent and Transparent to nearly opaque while Alexandrite is Transparent and Transparent to nearly opaque in appearance.