Tortoiseshell and Sillimanite Optical Properties

Tortoiseshell

Sillimanite

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1 Optical Properties

1.1 Luster

Not Available

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Not Available

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Gemmological Tables (2004)

Transparent, Translucent

1.5 Refractive Index

1.540-1.5601.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Not Available

Orthorhombic

1.8 Birefringence

Not Available0.020-0.022

0 0.296

1.9 Clarity

OpaqueUlrich Henn and Claudio C. Milisenda

Transparent

Tortoiseshell and Sillimanite Optic Character

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

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Tortoiseshell and Sillimanite Transparency

Similar to their colors, Tortoiseshell 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, Tortoiseshell is Gemmological Tables (2004) while Tortoiseshell is Gemmological Tables (2004) in appearance.