Opal and Coral Optical Properties

Opal

Coral

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Not Available

1.2 Pleochroism

None

AbsentWalter Schumann

1.3 Dispersion

NoneNone

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

Translucent

1.5 Refractive Index

1.37-1.521.486-1.658

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

1.8 Birefringence

Not Available0.160-0.172

0 0.296

1.9 Clarity

Transparent

Translucent

Opal and Coral Optic Character

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

Compare Semi Precious Gemstones

Opal Vs Amethyst

Opal Vs Lehsunia

Opal Vs Alexandrite

Opal and Coral Transparency

Similar to their colors, Opal and Coral 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.