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Benitoite
Benitoite

Sillimanite
Sillimanite



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Benitoite
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Sillimanite

Benitoite and Sillimanite Optical Properties

Optical Properties

Luster

Vitreous
Vitreous, Subadamantine, Silky

Pleochroism

O = colorless; E = purple
Colourless to pale brown to yellow

Dispersion

0.040.02
0.005 1
👆🏻

Transparency

Transparent
Transparent, Translucent

Refractive Index

1.757-1.8041.653-1.685
1 3.25
👆🏻

Optic Character

-
-

Crystal System

Hexagonal
Orthorhombic

Birefringence

0.0470.020-0.022
0 0.296
👆🏻

Clarity

Transparent
Transparent

Benitoite and Sillimanite Optic Character

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

Benitoite and Sillimanite Transparency

Similar to their colors, Benitoite 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, Benitoite is Transparent while Benitoite is Transparent in appearance.