Sillimanite and Sunstone Optical Properties

Sillimanite

Sunstone

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Optical Properties

Luster

Vitreous, Subadamantine, Silky

Vitreous

Pleochroism

Colourless to pale brown to yellow

Weak or absentWalter Schumann

Dispersion

0.020.01

0.005 1

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Transparency

Transparent, Translucent

Transparent, Translucent, Transparent to translucent

Refractive Index

1.653-1.6851.53-1.55

1 3.25

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Optic Character

Crystal System

Orthorhombic

Triclinic

Birefringence

0.020-0.0220.007-0.010

0 0.296

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Clarity

Transparent

Transparent to translucent

Sillimanite and Sunstone Optic Character

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

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Sillimanite and Sunstone Transparency

Similar to their colors, Sillimanite and Sunstone 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.