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Alunite
Alunite

Alexandrite
Alexandrite



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Alunite
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Alexandrite

Alunite and Alexandrite Optical Properties

Optical Properties

Luster

Pleochroism

Dispersion

Transparency

Refractive Index

Optic Character

Crystal System

Birefringence

Clarity

 
Vitreous, Pearly
-
0.02
-
1.572
-
Trigonal
0.020
-
 
Vitreous
-
0.02
Transparent, Transparent to nearly opaque
1.739-1.770
Biaxial/+
Orthorhombic
0.007-0.010
Transparent

Alunite and Alexandrite Optic Character

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

Alunite and Alexandrite Transparency

Similar to their colors, Alunite 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, Alunite is while Alunite is in appearance.