Opal and Spinel Optical Properties

Opal

Spinel

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Vitreous

1.2 Pleochroism

None

Absent

1.3 Dispersion

None0.02

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

1.5 Refractive Index

1.37-1.521.73

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

Isometric

1.8 Birefringence

Not AvailableNot Available

0 0.296

1.9 Clarity

Transparent

TransparentUlrich Henn and Claudio C. Milisenda

Opal and Spinel Optic Character

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

Similar to their colors, Opal and Spinel 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.