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Alexandrite

Tsarstone collectors guide


Index of refraction

Index of refraction
In crystal optics, a number indicating the speed of the velocity of light in a vacuum or air to its velocity in a given crystal. The refractive index (RI) of a crystal can be expressed as ratio of the sine of the angle of incidence to the sine of the angle of refraction from Snell's law for any two media. Its conventional symbol is n. The higher refractive index of a stone, the greater brilliance, such as diamond with RI: 2.4173 for sodium light at 589.3 nm. When a velocity of light is decrease in a gemstone (dense material) it is always inversely proportional to the optical density. In single refractive or uniaxial mineral the indices are "w" for ordinary-ray and "e" for extraordinary-ray. In the double refractive biaxial stones the indices are "a" a minimum value, "b" an intermediate value and "x" a maximum value.
Bibliographic details
Page title Definition of Index of refraction
Author David Weinberg
Website title Alexandrite Tsarstone Collectors Guide
Date published 03 July 2010 04:46 UTC
Date accessed 07 June 2026 20:04 UTC
Permanent link http://w.alexandrite.com/viewpage.html?id=GG-094-00006
AMA style
David Weinberg. "Definition of Index of refraction". In Alexandrite Tsarstone Collectors Guide. July 03, 2010, 04:46 UTC. Available at: http://w.alexandrite.com/viewpage.html?id=GG-094-00006. Accessed June 07, 2026.
APA style
"Definition of Index of refraction". (2010, July 03). In Alexandrite Tsarstone Collectors Guide. Retrieved 20:04, June 07, 2026, from http://w.alexandrite.com/viewpage.html?id=GG-094-00006.
Bluebook style
"Definition of Index of refraction", http://w.alexandrite.com/viewpage.html?id=GG-094-00006 (last visited June 07, 2026).
Bluebook: Harvard JOLT style
See Alexandrite Tsarstone Collectors Guide, "Definition of Index of refraction", http://w.alexandrite.com/viewpage.html?id=GG-094-00006 (In crystal optics, a number indicating the speed of the velocity of light in a vacuum or air to its velocity in a given crystal. The refractive index (RI) of a crystal can be expressed as ratio of the sine of the angle of incidence to the sine of the angle of refraction from Snell's law for any two media. Its conventional symbol is n. The higher refractive index of a stone, the greater brilliance, such as diamond with RI: 2.4173 for sodium light at 589.3 nm. When a velocity of light is decrease in a gemstone (dense material) it is always inversely proportional to the optical density. In single refractive or uniaxial mineral the indices are "w" for ordinary-ray and "e" for extraordinary-ray. In the double refractive biaxial stones the indices are "a" a minimum value, "b" an intermediate value and "x" a maximum value. ) (as of Jun. 07, 2026, 20:04 GMT).
CBE/CSE style
David Weinberg. "Definition of Index of refraction". In Alexandrite Tsarstone Collectors Guide. 2010 Jul 03, 04:46 UTC.[Internet], Alexandrite Tsarstone Collectors Guide; 2010 Jul 03, 04:46 UTC [cited 2026 Jun 07]. Available from: http://w.alexandrite.com/viewpage.html?id=GG-094-00006.
Chicago style
David Weinberg, "Definition of Index of refraction", http://w.alexandrite.com/viewpage.html?id=GG-094-00006, (accessed June 07, 2026).
MLA style
"Definition of Index of refraction". Alexandrite Tsarstone Collectors Guide. 03 Jul 2010, 04:46 UTC. 07 Jun 2026 http://w.alexandrite.com/viewpage.html?id=GG-094-00006
MHRA style
David Weinberg, "Definition of Index of refraction", Alexandrite Tsarstone Collectors Guide, 03 July 2010, 04:46 UTC, http://w.alexandrite.com/viewpage.html?id=GG-094-00006 [accessed 07 June 2026].
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