Opal and Alexandrite Optical Properties

Opal

Alexandrite

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Vitreous

1.2 Pleochroism

None

Not Available

1.3 Dispersion

Albite Optical ..

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None

Rank: N/A (Overall)▶

Not Available

Rank: N/A (Overall)▶

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Fluorite Optical Properties

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0.044 (Anglesite Opt..)

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1.4 Transparency

Transparent, Translucent, Transparent to translucent

Transparent, Transparent to nearly opaque

1.5 Refractive Index

1.37-1.52

1.739-1.770

1.6 Optic Character

Not Available

Biaxial/+

1.7 Crystal System

Trigonal

Orthorhombic

1.8 Birefringence

Not Available

0.007-0.010

1.9 Clarity

Transparent

Opal and Alexandrite Optic Character

Opal and Alexandrite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Opal and Alexandrite 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 Alexandrite 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. Alexandrite has Biaxial/+ character.

Compare Semi Precious Gemstones

Opal Vs Amethyst

Opal Vs Lehsunia

Opal Vs Alexandrite

Opal and Alexandrite Transparency

Similar to their colors, Opal and Alexandrite 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.