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Sillimanite
Sillimanite

Alexandrite
Alexandrite



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Sillimanite
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Alexandrite

Sillimanite and Alexandrite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Vitreous
1.2 Pleochroism
Colourless to pale brown to yellow
Not Available
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Transparent, Transparent to nearly opaque
1.5 Refractive Index
1.653-1.6851.739-1.770
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Biaxial/+
1.7 Crystal System
Orthorhombic
Orthorhombic
1.8 Birefringence
0.020-0.0220.007-0.010
Achroite
0 0.296
1.9 Clarity
Transparent
Transparent

Sillimanite and Alexandrite Optic Character

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

Sillimanite and Alexandrite Transparency

Similar to their colors, Sillimanite 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, Sillimanite is Translucent and Transparent while Sillimanite is Translucent and Transparent in appearance.