Opal and Thulite Optical Properties

Opal

Thulite

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Vitreous

1.2 Pleochroism

None

Present

1.3 Dispersion

NoneNA

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

Opaque, Translucent, Opaque . May be translucent in thin backlit sections.

1.5 Refractive Index

1.37-1.521.695

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

Orthorhombic

1.8 Birefringence

Not Available0.006-0.018

0 0.296

1.9 Clarity

Transparent

OpaqueHerve Nicolas Lazzarelli

Opal and Thulite Optic Character

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

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Opal Vs Amethyst

Opal and Thulite Transparency

Similar to their colors, Opal and Thulite 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.