Iolite and Allanite Optical Properties

Iolite

Allanite

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1 Optical Properties

1.1 Luster

Vitreous

Not Available

1.2 Pleochroism

Not Available

1.3 Dispersion

NANA

0.007 1

1.5 Transparency

Transparent, Translucent, Transparent to translucent

Not Available

1.6 Refractive Index

1.52-1.561

1 3.25

1.7 Optic Character

Not Available

1.8 Crystal System

Orthorhombic

Not Available

1.9 Birefringence

Not Available0.013-0.036

0 0.296

1.13 Clarity

Transparent to translucent

Not Available

Iolite and Allanite Optic Character

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

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Iolite and Allanite Transparency

Similar to their colors, Iolite and Allanite 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, Iolite is Translucent, Transparent and Transparent to translucent while Iolite is Translucent, Transparent and Transparent to translucent in appearance.