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Bertrandite
Bertrandite

Alexandrite
Alexandrite



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Bertrandite
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Alexandrite

Bertrandite and Alexandrite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous
Vitreous
1.2 Pleochroism
none.
Not Available
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
TransparentAnthony et al, Handbook of mineralogy (2001)
Transparent, Transparent to nearly opaque
1.5 Refractive Index
1.583-1.6141.739-1.770
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Biaxial/+
1.7 Crystal System
Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21
Orthorhombic
1.8 Birefringence
Not Available0.007-0.010
Achroite
0 0.296
1.9 Clarity
TransparentAnthony et al
Transparent

Bertrandite and Alexandrite Optic Character

Bertrandite and Alexandrite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Bertrandite and Alexandrite 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 Bertrandite and Alexandrite 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.

Bertrandite and Alexandrite Transparency

Similar to their colors, Bertrandite and Alexandrite 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, Bertrandite is Handbook of mineralogy (2001) and TransparentAnthony et al while Bertrandite is Handbook of mineralogy (2001) and TransparentAnthony et al in appearance.