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Topaz
Topaz

Onyx
Onyx



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Topaz
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Onyx

Topaz and Onyx Optical Properties

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Optical Properties

Luster

Vitreous
Vitreous

Pleochroism

Weak
-

Dispersion

0.010.01
0.005 1
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Transparency

Transparent
Translucent, Opaque, Translucent to opaque

Refractive Index

1.606-1.6441.530-1.543
1 3.25
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Optic Character

-
-

Crystal System

Orthorhombic
Trigonal

Birefringence

0.008-0.011-9999
0 0.296
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Clarity

TransparentUlrich Henn and Claudio C. Milisenda
OpaqueHerve Nicolas Lazzarelli

Topaz and Onyx Optic Character

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

Topaz and Onyx Transparency

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