Opal and Onyx Optical Properties

Opal

Onyx

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Vitreous

1.2 Pleochroism

None

Not Available

1.3 Dispersion

NoneNA

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

Translucent, Opaque, Translucent to opaque

1.5 Refractive Index

1.37-1.521.530-1.543

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

1.8 Birefringence

Not AvailableNot Available

0 0.296

1.9 Clarity

Transparent

OpaqueHerve Nicolas Lazzarelli

Opal and Onyx Optic Character

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

Compare Semi Precious Gemstones

Opal Vs Amethyst

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Opal and Onyx Transparency

Similar to their colors, Opal 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, Opal is Translucent, Transparent and Transparent to translucent while Opal is Translucent, Transparent and Transparent to translucent in appearance.