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Alexandrite
Alexandrite

Sillimanite
Sillimanite



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Alexandrite
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Sillimanite

Alexandrite and Sillimanite Optical Properties

Optical Properties

Luster

Vitreous
Vitreous, Subadamantine, Silky

Pleochroism

-
Colourless to pale brown to yellow

Dispersion

0.020.02
0.005 1
👆🏻

Transparency

Transparent, Transparent to nearly opaque
Transparent, Translucent

Refractive Index

1.739-1.7701.653-1.685
1 3.25
👆🏻

Optic Character

Biaxial/+
-

Crystal System

Orthorhombic
Orthorhombic

Birefringence

0.007-0.0100.020-0.022
0 0.296
👆🏻

Clarity

Transparent
Transparent

Alexandrite and Sillimanite Optic Character

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

Similar to their colors, Alexandrite and Sillimanite 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.