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Alexandrite
Alexandrite

Opal
Opal



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Alexandrite
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Opal

Alexandrite and Opal Optical Properties

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Optical Properties

Luster

Vitreous
Vitreous, Pearly

Pleochroism

-
None

Dispersion

0.020.01
0.005 1
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Transparency

Transparent, Transparent to nearly opaque
Transparent, Translucent, Transparent to translucent

Refractive Index

1.739-1.7701.37-1.52
1 3.25
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Optic Character

Biaxial/+
-

Crystal System

Orthorhombic
Trigonal

Birefringence

0.007-0.010-9999
0 0.296
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Clarity

Transparent
Transparent

Alexandrite and Opal Optic Character

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

Alexandrite and Opal Transparency

Similar to their colors, Alexandrite and Opal 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, Alexandrite is Transparent and Transparent to nearly opaque while Alexandrite is Transparent and Transparent to nearly opaque in appearance.