Opal and Grossular Optical Properties

Opal

Grossular

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Optical Properties

Luster

Vitreous, Pearly

Greasy, Vitreous

Pleochroism

None

Dispersion

0.010.02

0.005 1

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Transparency

Transparent, Translucent, Transparent to translucent

Refractive Index

1.37-1.521.730-1.760

1 3.25

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Optic Character

Crystal System

Trigonal

cubic

Birefringence

-99990.020

0 0.296

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Clarity

Transparent

TransparentUlrich Henn and Claudio C. Milisenda

Opal and Grossular Optic Character

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

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