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Alexandrite
Alexandrite

Umbalite
Umbalite



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Alexandrite
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Umbalite

Alexandrite and Umbalite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous
Not Available
1.2 Pleochroism
Not Available
Not Available
1.3 Dispersion
NA0.02
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Transparent to nearly opaque
TransparentGemdat.org, Management Team (2012)
1.5 Refractive Index
1.739-1.7701.730-1.820
Agate Opal
1 3.25
1.6 Optic Character
Biaxial/+
Not Available
1.7 Crystal System
Orthorhombic
Not Available
1.8 Birefringence
0.007-0.010Not Available
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentGemdat.org

Alexandrite and Umbalite Optic Character

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

Similar to their colors, Alexandrite and Umbalite 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.