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Sillimanite
Sillimanite

Topaz
Topaz



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Sillimanite
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Topaz

Sillimanite and Topaz Optical Properties

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Optical Properties

Luster

Vitreous, Subadamantine, Silky
Vitreous

Pleochroism

Colourless to pale brown to yellow
Weak

Dispersion

0.020.01
0.005 1
👆🏻

Transparency

Transparent, Translucent
Transparent

Refractive Index

1.653-1.6851.606-1.644
1 3.25
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Optic Character

-
-

Crystal System

Orthorhombic
Orthorhombic

Birefringence

0.020-0.0220.008-0.011
0 0.296
👆🏻

Clarity

Transparent
TransparentUlrich Henn and Claudio C. Milisenda

Sillimanite and Topaz Optic Character

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

Sillimanite and Topaz Transparency

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