All else held constant, the stronger the phenomenon of iridescence the more valuable the gem. In opals, larger patches of color, greater saturation of color and more individual colors are more desirable than tiny points or single colors.
Iridescence
Reflection of light off internal features in a gem, giving rise to a rainbow like play of colors.
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Iridescence
This refers to the optical effect whereby prismatic colours, similar to the ones seen on oil films, can be seen.
iridescence The exhibition of prismatic (rainbow) colors on the surface of a gem. See also orient, overtone.
Iridescence
The play of color in a gemstone resulting from inclusions or layers of minerals.
Karat
Unit of measurement that indicates the quantity of fine gemstone specimens and minerals like diamonds or opals.
Iridescence: The play of colors seen within a gemstone as a result of inclusions interfering with light entering the stone.
IRIDESCENCE - Prismatic colors inside or on the surface of a material caused by light interference from thin layers of differing refractive indices. These layers may be thin films of liquid, gas or solid.
Iridescence: This is the rainbow like color effect seen in some gems and is caused by cracks or structural layers breaking up light into spectral colors. Fire agate is a gemstone that shows this phenomenon to good effect.
Iridescence
Spectral colors observed inside or on a gemstone. It is caused by light passing through layers of differing refractive indexes. The colors seen in Opals are a result of iridescence.
IRIDESCENCE. Descriptive of prismatic colours appearing within a crystal.
ISOMETRIC. The cubic system in crystallography.
JAGERS. Bluish-white diamonds of modern cut; originally diamonds from the Jagersfontein mine.
iridescence
The luminous property that some gemstones like opal and moonstone have, whereby they appear to contain many different and changing colours
jabot
A jewelled tie pin, popular during the Art Deco period ...
Iridescence Effect caused by the interference of light on thin films within the gemstone.
Iridescence flashes of colors, which appear on the surface of the labradorite feldspar is known as Labradorescence. Labradorescence is an exclusive optical phenomenon that has solely shown by the feldspar gem Labradorite in this earth.
Iridescence in Pearls (Photos: Public Domain)
The iridescent quality of nacre (or mother-of-pearl) is due to the fact that the thickness of the aragonite platelets are about 0.5 micrometres, which is comparable to the wavelength of visible light.
Iridescence - the play of colors due to surface or internal interference. Labradorite exhibits internal iridescence whereas hematite and sphalerite often show the surface effect.
Iridescence
Exhibition of rainbowlike colors on a pearl surface. It is caused by the overlapping of successive layers, which breaks up light falling on the surface.
Irritant ...
Iridescence
The spectrum of colors present on the surface of a gemstone or inside it.
Kimberlite ...
Iridescence is an interference phenomenon that produces a prismatic, rainbow-like play-of-colors within, or on the surface of a gemstone. The effect may be caused by plate-like inclusions or mineral layers of differing refractive index.
The iridescence occurs in the thin outer aragonite layer of the ammonite shell, which is often assembled into triplets with a protective quartz top and a shale backing.
Sheen...The iridescence of light reflected from the surface of a stone. ie: moonstone
Silk...Fine rod like crystals embedded in a crystal
Skarn...Contact rock of igneous silicate masses with limestone.
Iridescence is caused by the reflection of light from the jewel.
- LAB RUBY (SAPPHIRE)
A lab ruby (or sapphire) is a synthetic (laboratory-made) stone.
The October birthstone is one of the most lustrous and radiant of gems - an ever-changing depth of fiery iridescence - ever refracting, ever reflecting, always giving wonder and delight.
It is Opal. And it just might possibly be the perfect gift! ...
iridesce The present term describing something displaying iridescence. iridescence Light effect causing a mineral to display a play of colors on an apparently monocolored surface.
Some inclusions give obsidian a metallic sheen, while internal bubbles or crystals produce a "snowflake" effect (called snowflake obsidian) or an iridescence seen as flashes of color.
Winter 1964, Treated black opal and its patchy iridescence, p. 242, 2pp.
Summer 1965, The Origin of Color in Opal, p. 291, 8pp.
Summer 1966, A cat's-eye opal, p. 60, 2pp.
Spring 1967, Oolitic opal, p. 149, 2pp.
In addition to cracking, loss of water causes loss of iridescence, therefore it might need to be oiled regularly to keep the water inside. Opal also must be protected from detergents that dry the gem.
Iridescence: Iridescence is a phenomenon. A soft sheen of prismatic colors appears to float over the top of a gemstone's surface, changing as the light source moves.
Common opal is a fairly unimpressive milky-white rock, he said; fire opal glows orange or red; and precious opal, the most valuable, glimmers with iridescence.
"I've never seen any fire opal here," Gustin said. "Now, that's what the world's seeking.
In addition to their beautiful luster, many pearls display iridescence, and this is due in part, as in the case of the pearly lining of the shell (mother of pearl) to overlapping of successive layers, like the overlapping of shingles on a roof.
This iridescence is known as schiller but in moonstone it is called adularescence. Clarity ranges from transparent to translucent. Rainbow moonstone is milky white with a rainbow colored sheen.
There are three major types of opals: common opal, opalescent precious opal (white or black, with a rainbow-like iridescence caused by tiny crystals of cristobalite), ...
Orient is the depth, iridescence and translucence of the nacre layering. Luster is the glow or shine created when light travels through the nacre of the Pearl and is different than the light reflected off the surface of a Pearl.
One of the two principal varieties of opal (as contrasted with common opal) which exhibits iridescence due to a play of spectral colours when light falls upon its surface.
Synthetic - A clear milky color when looked at from direct light, Opalescent Quartz has an iridescence that give it its namesake. When placed on black or dark material, it really shines, especially on a necklace with darker colored beads and pendants.
Contra luz (also spelled contraluz) opals are transparent opals that show a brilliant play of iridescence only when light shines through the stone.
" I inquired, thinking that surely he had kept for the last, as a surprise, this gem whose reputation f or black iridescence and special hardness had traveled all the way to New York.
schiller (n) a term meaning "twinkle" in German used to describe iridescence beneath the surface of a stone. Schiller is used more generically than other terms such as adulerescence (which refers to the iridescence in moonstones) or opalescnce (opal).
The quality of pearls is judged by the orient, which is the soft iridescence caused by the refraction of light by the layers of nacre, and lustre, the reflectivity and shine of the surface.
Variety of Quartz or Feldspar Mineral that is flecked with particles of hematite and mica that cause a shiny iridescence
Color: Green, orange, brown, yellow, blue, or gray
Transparency: Translucent to opaque
Hardness: 6.5 ...
The most valuable pearls are perfectly symmetrical, large, naturally produced, and have a shimmering iridescence (called orient luster).
This radial and onion-like arrangement of aragonite and nacre is highly regular and is the source of pearls iridescence and unique luster.
Precious opal, as compared to common opal, offers the rainbow iridescence that has been so highly prized since Roman times. Australia boasts the largest opals: a 26,350-carat gem-quality white opal found in 1989, and a 1,982.
A rainbow-like iridescence reminiscent of the weather phenomenon called Aurora Borealis, or Northern Lights.
A type of transparent or translucent Feldspar which displays strong iridescence (labradorescence). It is a grayish-green but displays bright flashes of green, blue and sometimes yellow-gold colors when viewed from different angles.
Yellow opal is a form of opal, a translucent mineral, known for its rich iridescence, consisting of hydrated silica of variable colours. It is most predominant in volcanic areas, especially where there is hot-spring activity.
They have a shimmering iridescence which is called orient luster. The principal oyster beds lay in the Persian Gulf, along the coasts of India and Sri Lanka, and in the Red Sea.
Short for "Aurora Boreal" (Northern lights), a term that denotes iridescence, especially in crystals, rhinestone, or synthetic stones used in making costume jewelry.
A semi-precious stone with a rainbow-like iridescence which are categorized as three types: opalescent precious opals, yellow-red fire opals and the common opal
Orient
The characteristic sheen of fine natural and cultured pearls ...
Most distinguishing features:
Green-blue-purple iridescence is indicative, as is a brownish-bronze colour on fresh surfaces.
Industrial/economical uses:
Mined as an ore of copper, but not as important as chalcopyrite.
The name is from an Indian word meaning simply "stone". Three types are precious opal, with a rainbow iridescence, fire opal, named for its red-orange color, and common opal which lacks the iridescence of precious opal.
Strass (or "Strasse"): A brilliant glass with high light refraction and exceptional iridescence, (essentially consisting of a complex borosilicate of lead and potassium), used to manufacture artificial gemstones.
Iridescence - Play of prismatic colors on the surface of a mineral. (Goethite, Lepidochrosite)
Isometric System - A crystallization system having three equal-length axes at 90 degrees to each other.
(Pyrite, Garnet, Fluorite, etc.) ...
A calcareous concretion formed in the body of a mollusk and possessing iridescence (orient)
Pennyweight
A measurement of weight used with precious metal, twenty pennyweight equal one troy ounce, abbreviated dwt.
The rainbow-like iridescence is caused by tiny crystals of cristobalite. Many opals have a high water content - they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Opals have a hardness of 5.5 to 6.
An iridescent object displays many lustrous, changing colors. Iridescence is caused by the reflection of light from the jewel.
IRIDIUM ...
Iridescent: A display of lustrous rainbow-like colors. The colors seen in an oil slick or mother of pearl are good examples of iridescence. The spectrum of colors change as the observers viewing position is altered. Synonymous with "Pearlescent".
This iridescence is the result of a deposit of a very thin layer of metallic atoms on the lower surface of the rhinestone. It is very susceptible to scratching, so must be stored carefully.
Andalusite
Faceted andalusite stones give a play of red, green, and yellow colors that resembles a muted form of iridescence. Andalusite belongs to the same family as kyanite and sillimanite.
Describes a thin, air-filled crack within translucent gems that creates iridescence.
ivorine
See French Ivory.
Contra Luz Opal: Transparent opals that are usually faceted and will show iridescence when light shines through the stone.
 See also: Color, Stone, Jewel, Surface, Gemstone
  
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