Demantoid and Onyx Optical Properties

Demantoid

Onyx

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1 Optical Properties

1.1 Luster

Adamantine

Vitreous

1.2 Pleochroism

None

Not Available

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Gemmological Tables (2004)

Translucent, Opaque, Translucent to opaque

1.5 Refractive Index

1.880-1.8901.530-1.543

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

cubic

Trigonal

1.8 Birefringence

Not AvailableNot Available

0 0.296

1.9 Clarity

TransparentUlrich Henn and Claudio C. Milisenda

OpaqueHerve Nicolas Lazzarelli

Demantoid and Onyx Optic Character

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

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Demantoid and Onyx Transparency

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