Asterism" is a term, which is most commonly used in gemology. It refers a kind of special optic phenomenon that has been seen in several gems.
Star Stones (Asterism)
When parallel, needle-like inclusions, or tube-like channels, are oriented along two or more of the crystal faces of a mineral, and when that stone is cut as a domed cabochon, ...
ASTERISM - The optical phenomenon of seeing a rayed figure in the form of a star. This is caused by the reflection of light from minute oriented and aligned needle-like inclusions.
Asterism: The star effect displayed by certain gems with properly intersecting inclusions. Gems of this variety are always cut en cabochon (see Cabochon cut).
Baroque: Odd-shaped pearls formed during cultivation.
Asterism: Also know as the star effect, this is a reflection effect that appears as two or more intersecting bands of light across the surface of a gem.
Asterism
The appearance of a rayed figure or rayed star in a gemstone, caused by the reflection of light from minute inclusions. Star Sapphires and Star Rubies are two well-known examples of gemstones featuring a rayed star.
Asterism
A star effect displayed by certain gems with intersecting inclusions. (see 'rutiles')
Bruto
The Spanish word for "rough", as in rough or raw gemstone and mineral material.
Asterism - Four-rayed or six-rayed bands (cat's eye) caused by light reflecting from needle-like inclusions within some gem crystals.
Bail - A metal attachment used for hanging a pendant from a chain or cord.
Asterism The star effect that you see in star sapphires or rubies, for example. This is usually caused by tiny silk rutile inclusions in the stone. The effect can be four- or six- rayed.
Asterism
Asterism is the star effect that appears on some gemstones. This star effect is a reflection that appears as two or more intersecting bands of light across the surface of a gem. Usually asterism is found in Ruby, Sapphire and Garnet.
Asterism: An optical effect sometimes seen in phenomenal gemstones like star sapphires. A six-ray star should be visible over the dome of a cabochon-cut gemstone when minute needle-inclusions are arranged just so.
Asterism
Star effect seen in some stones when cut en cabochon.
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Asterism
An asterism is a star-like luminous effect that reflects light in some gemstones, like star sapphires and star garnets.
Atlas Beads
Pentagonal satin glass beads with corners ground off.
asterism
A star-like light effect that is usually only seen in cabochons.
aurora borealis ...
asterism
The luminous property that some gemstones like Star Sapphires have, whereby their inclusions are aligned in such a way that they reflect light in the pattern of a 4, 6 or 12 rayed star ...
Asterism
Asterism is the name for the star shape light that reflects from certain gemstones.
Asterism
A luminous star like effect exhibited in some gemstones like star sapphires, garnets and rubies. asterismAsterism is caused by inclusions of tiny, parallel, rutile needles and may result in four, six or even twelve rayed stars.
ASTERISM
An asterism is a star-like luminous effect that reflects light in some gemstones, like star.
AUSTRALIAN RUBY ...
Asterism:
Light rays form star-like effect in certain cabochon cut gemstones. They can be four-rayed, 6-rayed or (rarely) 12.
Band Detailing: ...
ASTERISM A "star" or pattern of rays, typically six rays, crossing in a single spot on a cabochon cut gemstone when viewed under a single source of light.
Asterism...Stones containing suitably oriented rod like inclusions or channels, that are cut as cabochon in the correct direction show this star effect. Star effect.
Asterism
Star effect caused by light reflecting off inclusions inside a diamond
Aventurescence ...
Asterism
The star like effect are a reflection of light from the inclusion, seen only on suitable stones, which are cut to cabochons with the inclusions in the correct directions.
Atom
The smallest part of an element which retain the properties of it.
Asterism: 6 (more rarely 12)-rayed star due to oriented rutile needles.
U.V. Fluorescence: varies with place of origin (Fe content); ...
asterism
In gemological terms, asterism is a special optical property that manifests as a star-like pattern on the surface of a gemstone. Depending on the crystal structure, the star may have four, six, or even twelve rays.
Asterism: A star shaped light that reflects from some gemstones.
ATW: Approximate Total Weight, measured in carats, of a gemstone.
The asterism of the star garnets is caused by asbestiform pyroxene and amphibole inclusions.
Star, or asterism, is a phenomenon that appears when light is reflected from oriented inclusions in corundum. These silk inclusions are exsolved needles of rutile, oriented along three directions in a basal plane.
Introducing asterism by exsolving of silk
BC
1960's: Gueda sapphire to blue (Crowningshield 1966, 1970, Beesley, 1982.)
1949, Burdick and Glenn patent ...
Star Sapphire (Asterism)
Certain varieties of sapphire can exhibit a six-pointed "star" or "asteriated" effect (above, right) from light reflections bouncing off of microscopic needle-shaped rutile crystals (also referred to in the ruby trade as ...
Star garnets are almandines that exhibit an asterism. Almandine has a hardness of 7.5 and a specific gravity of 3.85-4.20.
Asterism:An optical phenomenon displayed by certain gemstones such as rubies or sapphires that reflects the shape of a star on the surface of a cabochon cut from the stone. The stars may have four, six, or twelve rays.
Some apatite stones show a cat's eye asterism. This stone is rarely used in jewelry because it is brittle and soft. Apatite comes from the Greek word for "deceit," because it was easily confused with other minerals.
asbestos amphibole Any extremely fibrous mineral of the amphibole group asterism Effect exhibited on some minerals (usually only in polished cabochons) causing it to reflect a billowy, ...
Special effects, such as asterism, chatoyancy, adularescence and opalescence cannot be achieved without a cabochon cut. Calibre cut: A style of gemstone cut, usually utilized for small sizes.
The star effect, known to gem lovers as Asterism, appears as rays of a star across the domed surface of the gem and is most often seen in Ruby, Sapphire, Quartz, Garnet and Spinel.
Star-effect or "asterism" is caused by the dense inclusions of tiny fibers of rutile (also known as "silk"). The stars are caused by the light reflecting from needle-like inclusions of rutile aligned perpendicular to the rays of the star.
Trapiche emeralds are rare, valuable emeralds that have a black, six-rayed star within them, caused by black carbon impurities (the star is not an asterism). These stones are usually cabochon cut to display the beautiful spoke-like star.
When in dense, parallel groupings, these inclusions can actually enhance by allowing the polished Sapphires to exhibit asterism.
Here too, the mineral rutile is involved: having formed a star-shaped deposit within the ruby, it causes a captivating light effect known by the experts as asterism.
This effect, called asterism, is caused by light reflecting off tiny rutile needles, called "silk," which are oriented along the crystal faces.
Asteria: Asteriated or asterism refer to a property possessed by some gem stones when cut cabochon or when viewed in transmitted light, of reflecting the light as a star, or surrounding the light source with radiating rays.
Star garnets: Almandines that exhibit an asterism.
Star Sapphires: Natural sapphires that exhibit an asterism. These can be quite valuable if the star is centered and well-defined.
Stater: A silver coin from ancient Greece.
A "star ruby" is a ruby that exhibits an asterism, a six-pointed star of light (when cut as a cabochon). The world's biggest star ruby is the Rajaratna, which weighs 2,475 carats.
Small rutile needles present in gems are responsible for an optical phenomenon known as asterism. Asterated gems are known as "star" gems.
One variety of rose quartz holds an asterism effect and is called star quartz.
Chanthaburi
Consult list of gems available on the Chanthaburi market...
Milk Quartz : white, translucent to opaque, may display diasterism.
Rose Quartz : pale, pink, translucent color of quartz.
Rutilated Quartz : contains acicular (needles) inclusions of rutile.
Enhancements
Cat's eye is occasionally irradiated to improve asterism and color.
More information on gemstone enhancements.
Cymophane (Cat's Eye) ...
Sapphires with inclusions of tiny, rutile needles exhibit an optical property called asterism. This is the star shaped effect seen in star sapphires and is usually only seen in cabochon cuts.
The Rajaratna is the biggest-known "star ruby" (a ruby that exhibits an asterism, a six-pointed star of light, cut as a cabochon). It weighs 2,475 carats.
RATI ...
Diffusion of color or asterism in corundum at or near the surface
Usually
Rarely ...
(BLACK STAR OF INDIA) Black star of India is another name for Black Star diopside (CaMgSi2O6), an opaque black gem with a white, four-rayed star (an asterism). It has a hardness of 5.5 and a specific gravity of 3.3 - 3.6.
Special, needle-like inclusions cause the spectacular optical phenomenon called cat’s eye and asterism displayed by chrysoberyl and corundum (sapphire and ruby) respectively.
Some inclusions decrease the value of a stone, but some, like rutile forming asterisms in star sapphires and needles in rutilated quartz and tourmalated quartz, are prized. The tumbled stones in the photo to the left are tourmalated quartz.
Usage: Almandite is said to be particularly useful for strengthening the heart, to inspire love and to perceive truth.
Some Almandine garnets display asterism when polished as cabochons. Such specimens are known as "Star Garnets".
A precious gemstone (a type of corundum) that ranges in color from blue to pink to yellow to green to white to purple to pink-orange. Six-sided asterisms (stars) sometimes occur in star sapphires.
This type of cut will result in reflections of light in a star pattern across the stone, known as Asterism or "Star Rubies." Natural star rubies are extremely rare and those available are usually synthetic.
Almandine is the most common type in the Garnet family. It is violet-tinged and ranges in color from deep red to reddish-brown. Some Almandine garnets display asterism when polished as cabochons and are known as "Star Garnets".
rutile (n) the mineral titanium dioxide. Rutiles sometimes feature as inclusions in other gemstones. Rutile inclusions are often needle-like and may also produce asterism effects, e.g., in rubies.
An inclusion is a imperfection or flaw in a diamond or other gemstone that affects the stone's clarity. Many inclusions decrease the value of a stone, but some, like rutile forming asterisms in star sapphires and needles in rutilated quartz and ...
 See also: Stone, Color, Gemstone, Crystal, Mineral
  
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