Optical Birefringence in Gemstones & Minerals
The term "birefringence" describes the optical phenomenon of double refraction as a single beam of light travels through a transparent, molecularly ordered material, ...
Birefringence: This property is when there are two different refractive indices of light that are noticed, which cross-polarized when it enters matter.
Birefringence Some gemstones are singly refractive: they have only one refractive index. Other gemstones (in fact, most) are doubly refractive: they have two different refractive indices.
BIREFRINGENCE. Double refraction of light of crystal minerals.
BIZEL. Portion of brilliant-cut diamond above the girdle.
BLEBBY. Blisters or bubbles in a crystal mineral ...
Birefringence: 0.006
Pleiochroism: weak to moderate: blue and greenish blue in lighter or darker tones All text and images, unless otherwise designated, © 2008 Barbara Smigel ...
Birefringence
The numerical measurement of double refraction in gemstones.
Blocking
The process of placing the facets on a stone.
BIREFRINGENCE
Birefringence is another name for double refraction. In doubly-refractive stones, the light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index.
birefringence - A technical term for the separation by a doubly refracting crystal of a single light ray into two rays moving at different speeds. If the difference is too small to be seen with the eye, a dichroscope may be used.
BIREFRINGENCE: The strength of double refraction measured by taking the difference between the high and low refractive indices of a doubly refractive gemstone.
CHANDRA-RASI: Moon sign.
Birefringence: Low (0.005-0.009)
Dispersion: Low (about 0.014)
Pleochroism: weak to none, except in pink stones. Some yellow varieties may show a weak yellow to pink dichroism.
Color: see above.
U.V.
Birefringence
The measurements (the high and low index) taken by double refractive stones of light travel (except optic axis) with different speed trough the crystal.
Birefringence...Same as double refraction. Splits rays of light passing through a transparent object as glass or crystal.
Botryoidal... Resembling a bunch of grapes in rounded masses of a mineral.
Birefringence is the difference in value between the highest and lowest refractive indices in a doubly refractive (anisotropic) material.
Birefringence:
per Joel Arem: 0.004 to 0.008 per Cally Hall: 0.008
Optic Character ...
Strong birefringence can make the zircon fuzzy looking face up so care should be taken in orienting the stones while cutting.
Due to its low hardness, zircon should be held with great care, and each stone should be packed individually.
Chanthaburi ...
Refraction and Birefringence:
When a ray of light passes from air into a denser medium, such as a gemstone, part is reflected from the surface and part enters the gem material.
It also resembles rose quartz and pink topaz, but has clearer birefringence (double refraction) than both rose quartz and morganite. It is most difficult to distinguish from pink tourmaline.
Sphene’s magnificent fire, unique color shades, strong pleochroism, adamantine (diamond-like) luster and double refraction (birefringence) make it ideal for earrings and pendants that catch the light, ...
There are many different types of LC phases, which can be distinguished based on their different optical properties (such as birefringence).
Birefringence - The degree of double refraction in a crystal. (Calcite)
Blady - A flattened habit resembling a knife blade. (Barite)
Borates - Minerals containing the borate (BO3) radical as a major component. (Colemanite) ...
COLOR: various colors, except for red.
INDEX OF REFRACTION: 1.76 - 1.78
BIREFRINGENCE: 0.009
HARDNESS: 9
CLEAVAGE: none, although there is a rhombic parting
CRYSTAL SYSTEM: trigonal
PLEOCHROIC: strongly ...
Burmese gems are often marred by small platelet inclusions, which may give some stones a sleepy appearance
The strong birefringence (0.036) of peridot can also give stones a slightly sleepy look.
Its wide range of colour, relatively high refractive index, colour dispersion modestly higher than corundum, good hardness as well as lack of birefringence and cleavage raise it above other, even well known precious stones.
52 - 1.68 that can vary with mineral content of the stone. The Birefringence of the stone constitutes usually 1.55 with a variable Ultraviolet fluorescence. The Specific gravity is usually about 2.70.
the light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index. Calcite, peridot, zircon, tourmaline, and titanite are doubly-refractive stones. Birefringence is ...
thermal conductivity probes to distinguish diamond from imitations, and as moissanite had a high coefficient of thermal conductivity, it used to give false positives for diamond. Other simple optical checks, such as noticing its strong birefringence ...
 See also: Stone, Color, Crystal, Gemstone, Gem
  
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