gemstone glossary
agate a variety of chalcedony (kal-SED-uh-nee) with distinct banding, appearing as layers of colors and patterns, often dyed to enhance the natural colors. common sources include idar-oberstein in germany, uruguay and brazil among others. ultrasonic cleaning is usually safe, warm soapy water is best. alexandrite the transparent, color change variety of the mineral species chrysoberyl (KRIS-oh-bare-ul), appearing as grayish to bluish green in daylight and as brownish red to purple red in incandescent light. very rarely, this variety will also exhibit chatoyancy (cat's-eye). there are no known enhancements for this material. common sources include brazil, sri lanka and russia among others. ultrasonic cleaning is usually safe, warm soapy water is best. amazonite the blue-green variety of microcline (MY-cro-cline) feldspar, sometimes with white streaks which produce a slight sheen. tumbled pieces may be wax impregnated to hide cracks that reach the surface. common sources include india, the united states, the former ussr, and madagascar among others. avoid heat and rough handling. do not use ultrasonic cleaning, warm soapy water is best. amber the fossilized resin of trees, transparent to opaque, most commonly in tones of yellow, brown, and orange, and often seen with bits of insects or vegetative matter trapped within. heating and dyeing are common treatments to clarify or alter the color. common sources are the coasts of poland and the former ussr in the baltic region, though amber is found in other regions of the world as well. do not use ultrasonic cleaning, warm soapy water is best but take care not to scratch the surface if using a bristled brush. amethyst the transparent purple, bluish purple and reddish purple variety of quartz occasionally treated with heat to lighten dark purple crystals or to change the color to yellow, which is known as citrine. common sources include brazil, uruguay, and the united states among others. ultrasonic cleaning is usually safe, warm soapy water is best. andalusite (and-a-LOO-site) transparent to opaque material, found in shades of brown, yellow green and orangey brown. this material exhibits strong pleochroism with both orange and green many times visible through the top, or crown, of the faceted material. (pleochroism is the difference in light absorption along the different directions of crystal structure which results in more than one color visible, with or without rotation of the specimen; not to be confused with a multi-colored material with zones or bands of color.) sometimes this beautiful material is referred to as "poor man's alexandrite." chiastolite (ki-ASS-tow-lite) is the translucent to opaque variety seen in shades of gray to reddish brown with a dark cross pattern, resembling a greek cross. heating is a rare treatment used to alter the color. common sources are brazil and sri lanka among others. ultrasonic cleaning is usually safe, warm soapy water is best. avoid rough handling. apatite (AP-uh-tite) translucent to opaque material, rarely cut as a gemstone, occurring in colors of yellow, blue, violet, green, and sometimes colorless. chatoyant stones are sometimes seen, meaning they have a cat's-eye effect. common sources include brazil, canada, east africa and mexico among others. ultrasonic cleaning is not recommended, warm soapy water is best. heat should be avoided. aquamarine the transparent variety of light blue green to greenish blue beryl, named so because of its resemblance to seawater. rarely, a weak chatoyancy will be found in this material. heating is a routine treatment to enhance the color, so routine that nearly all aquamarine found on the market has been treated. the best material is found in brazil, however aquamarine is also found in russia, nigeria, and madagascar among other locales. ultrasonic cleaning is usually safe, except heavily included stones, however warm soapy water is best. avoid heat if the material contains liquid inclusions. aragonite (uh-RAG-oh-nite) a transparent to opaque mineral species found in colorless or white and in a variety of colors (red, yellow, brown, green, blue and violet) when impurities such as iron oxides and copper are present, though usually light in tone. availability is scarce with sources including austria, bolivia, england and italy among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and chemicals. aventurine a variety of quartz, translucent to opaque, and most commonly green. this material sometimes shows aventurescence or reflections of light like glitter due to inclusions of mica, oxides or pyrite crystals. common sources include brazil, india and russia among others. ultrasonic cleaning is usually safe, warm soapy water is best. beryl (other than emerald or aquamarine) transparent to opaque material appearing in shades of green, yellow, orange, pink, colorless, brown and black, and rarely red and blue. rarely beryl (BARE-ul) exhibits the phenomena chatoyancy (cat's-eye) and asterism (star). varieties of beryl are green beryl, too light or yellow to be considered emerald; golden beryl, green yellow to yellow brown, also called heliodor; morganite, pink, peach or violet; goshenite, colorless, sometimes used to imitate diamond; maxixe beryl, faded medium to dark blue; and red beryl, very rare, also known as bixbite. assumed common treatments are heating to improve the color of morganite, and irradiation to create yellow beryl from colorless beryl. common sources include brazil and madagascar among others. do not use ultrasonic cleaning, warm soapy water is best, but avoid strong soaps, heat and rough handling. calcite (KAL-site)a transparent to opaque mineral species found in nearly all colors, occasionally displaying the phenomenon chatoyancy (cat's-eye). marble and onyx marble are a couple of the variety names applied to calcite. dyeing and wax or plastic impregnation are common treatments to add color to marble varieties and to improve the luster. irradiation is occasional to change colors in marble. major sources are mexico and the united states. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling, heat and chemicals. carnelian the translucent orange-red variety of chalcedony (kal-SED-uh-nee), usually uniformly-colored, sometimes with faint banding. often dyed or heat-treated to enhance the natural color. most common sources are india, brazil and uruguay. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat as color could change. cat's-eye the semitransparent to semitranslucent, chatoyant variety of chrysoberyl (KRIS-oh-bare-ul), appearing in shades of yellow to yellowish or grayish green and brown to brownish yellow. very rarely this material also exhibits color change. there are no known treatments for this material. common sources include brazil, sri lanka and russia among others. ultrasonic cleaning is usually safe, warm soapy water is best. charoite (CHAR-oh-ite) semitranslucent to opaque purple aggregate with splotches and swirls of black, gray and white. charoite is a fairly abundant material and is fashioned in carvings and ornamental items, as well as in cabochons and beads. the major source for charoite is russia. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling. chinese writing stone an opaque, greenish-brownish-mauve type of jasper, a variety of chalcedony (kal-SED-uh-nee). common sources for jasper include germany, united states and russia among others. ultrasonic cleaning is usually safe, warm soapy water is best. chrysoberyl (KRIS-oh-bare-ul) transparent to opaque mineral species appearing in shades of yellow to yellowish or grayish green and brown to yellowish brown, and rarely light blue. the name is derived from greek chrysos, meaning golden, and beryllos, in reference to its beryllium content. this material was highly valued for thousands of years in asia, thought to provide protection from evil. there are no known treatments. common sources include brazil, sri lanka and russia among others. ultrasonic cleaning is usually safe, warm soapy water is best. chrysocolla (KRIS-oh-co-la) the vibrant green and blue-green variety of chalcedony, rich in copper mineral. common sources are the copper-mining areas in chile, the former ussr, zaire, and the united states. ultrasonic cleaning is usually safe, warm soapy water is best. chrysoprase (KRIS-oh-praze) the translucent, apple-green variety of chalcedony, perhaps the most valued variety of chalcedony. the best quality material comes from australia, other sources include brazil and the united states among others. ultrasonic cleaning is usually safe, warm soapy water is best. citrine the transparent yellow, orange or brownish orange variety of quartz, commonly treated with heat to create citrine from amethyst or to create a yellowish green citrine, known as honey quartz, from smoky quartz. practically all citrines have been heat-treated. common sources include brazil and spain among others. ultrasonic cleaning is usually safe, warm soapy water is best. avoid abrupt temperature changes, strong heat and acids. corundum (ko-RUN-dum) transparent to opaque mineral species found in all colors of the spectrum, generally classified into three varieties by range of color: blue sapphire (violetish blue to greenish blue), ruby (orange to purplish red and brownish red), and fancy sapphire (all colors except those which qualify as blue sapphire and ruby). this material can exhibit the phenomena color change and asterism (star) and very rarely chatoyancy (cat's-eye). varietal names are also applied to many colors in the fancy sapphire variety. for example, a highly prized medium pinkish orange to orange pink variety is referred to as padparadscha sapphire. heating is a common treatment and irradiation is an occasional treatment used to enhance the color and appearance of the material. common sources include sri lanka, australia, and east africa among others. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat, especially if treatment is known. diamond transparent to opaque mineral species with the chemical composition of carbon, and the hardest mineral on earth. diamond is generally found in a color range of light yellow, brown or gray to colorless, however diamond does occur in fancy colors, the unusual colors of dark yellow, brown and gray, as well as tones of blue, green, orange, pink, red, purple and black. on account of diamond's nature and its popularity, it has its own unique grading system, separate from that of other gem materials. irradiation, laser drilling and bleaching, filling and coating are occasional to common treatments performed to enhance the color and appearance of the material. common sources include africa, russia and australia among others. ultrasonic cleaning is usually safe unless heavily included, however warm soapy water is best. avoid heat and solvents if the material has been filled or coated. diopside (dye-OP-side) transparent to opaque mineral species occurring in shades of bluish green to yellowish green, brown and black, and rarely blue, violet, colorless and white. this material can exhibit the phenomena asterism (star, usually 4-rayed) and chatoyancy (cat's-eye). the variety chrome diopside is a transparent, medium dark vivid green, colored by chromium. there are no known treatments. common sources include myanmar, russia and south africa among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling. dumortierite (do-MORE-tee-air-ite) translucent to opaque dark blue to violet mineral species either found in its massive form or combined with colorless quartz, whereupon it is referred to as dumortierite quartz. dumortierite is used as an ornamental material and as cut in cabochons or beads. there are no known treatments. common sources include france, madagascar and norway among others, with the majority of the gem-quality material coming from nevada. ultrasonic cleaning is usually safe, warm soapy water is best. emerald transparent to translucent (on account of heavy inclusions), light to very dark green to blue green variety of beryl, sometimes exhibiting the phenomena of chatoyancy (cat's-eye) and rarely, asterism (star). oiling, sometimes containing green dye, is a routine treatment on heavily included material, performed to disguise blemishes, especially those reaching the surface and to enhance color. columbian is a trade name applied to the emeralds from columbia, the source of the finest emeralds on the current market. emeralds used in historical or period jewelry were mined in egypt. other sources of emerald include brazil and south africa among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat, rough handling and strong soaps. fluorite (FLOOR-ite) transparent to translucent, formerly known as fluorspar, occurring in a variety of colors - yellow, blue, green, pink, purple, orange and others. heat treating to lighten color is common. common sources include canada, the united states and england among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and rough handling. garnet a group of a multitude of mineral specie, six most common, transparent to opaque, occurring in nearly every color, generally not enhanced. almandite (ALL-man-dite) garnet is a reddish orange to red, purplish red to reddish purple species, sometimes exhibiting asterism (star). andradite (ANN-druh-dite) garnet is a yellow, green, brown and black species, rarely exhibiting chatoyancy (cat's-eye) or iridescence. demantoid (duh-MAN-toyd) is a variety of andradite garnet. grossularite (GRAHSS-you-lar-ite) garnet is a green, yellow, reddish orange and colorless species. hessonite and tsavorite (SAV-or-ite) are varieties of grossularite garnet. hydrogrossular (hie-droh-GRAHSS-you-lar) garnet is a green to bluish green, pink, white and gray species, sometimes referred to with the misnomers of african jade or transvaal jade. malaia (muh-LYE-uh) and color change garnets are varieties of a pyrope-spessartite mixture. pyrope (PYE-rope) garnet is a reddish orange, red, purplish red and colorless species, sometimes referred to with the misnomers of colorado ruby, cape ruby, or arizona ruby. rhodolite (ROE-doe-lite) garnet is a purplish red to reddish purple variety of a pyrope-almandite mixture. spessartite (SPESS-ar-tite) garnet is a yellowish orange to reddish orange species. common sources include the united states, south africa and australia among many others. ultrasonic cleaning is generally safe, though warm soapy water is generally best. avoid sudden changes in temperature. gemstone phenomena many gemstones and gem material display phenomena, or unusual optical effects, which add a special distinction to an already beautiful work of natural art. view the "gems in the spotlight" article here for descriptions of the different phenomena, including mention of the materials in which they are commonly seen and photos. glass (natural) transparent to opaque, amorphous and of varying chemical composition, occurring in shades of gray, black, brown, yellow, orange, red, and rarely green, blue and purple, occasionally exhibiting the phenomena iridescence, and rarely, chatoyancy (cat's-eye). varieties include obsidian, natural glass of volcanic origin; tektites, considered "splash" products created by meteor impacts, such as moldavite; and libyan desert glass, origin is uncertain. there are no known treatments. obsidian is found throughout the world, moldavite in czechoslovakia and other tektites in southeast asia and australia. ultrasonic cleaning is usually safe, warm soapy water is best. hematite (HEM-ah-tite) opaque mineral species occurring in gray and black with a metallic luster, typically seen in carvings, cameos, intaglios, cabochons and beads. there are no known treatments. common sources include england, canada and brazil among others. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat, rough handling and acids. hypersthene an iron-rich material of the mineral species enstatite, distinguished by a reddish iridescence due to inclusions of hematite, many times cut en cabochon. availability is scarce with sources including india, norway, germany and the united states. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and chemnicals. idocrase (EYE-doe-craze) transparent to opaque mineral species occurring in shades of yellow, green, yellowish brown, blue to greenish blue, gray and white. californite is a variety of idocrase, green to yellow mottled material, often with veining, occasionally referred to with the misnomer california jade. there are no known treatments. common sources include canada, russia and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling, heat and acids. iolite (EYE-oh-lite) transparent to translucent mineral species occurring in shades of blue and violet with very recognizable pleochroism, visible to the naked eye, as deep color seen along the length, nearly colorless when viewed across. this material is sometimes seen in green, gray, colorless, white and brown and not used as gem material. rarely, this material will exhibit the phenomena asterism (star), chatoyancy (cat's-eye) and aventurescence (glittery reflections of light). sometimes referred to with the misnomer water sapphire. there are no known treatments. common sources include sri lanka, myanmar and india among others. do not use ultrasonic cleaning, warm soapy water is best. avoid abrupt temperature changes and acids. jade group of two minerals, jadeite and nephrite, occurring in a wide range of colors, green being the most recognized, a rich emerald green the most prized. treatments are common, dyeing and wax impregnation the most common, heating also done. common sources include myanmar and new zealand among others. ultrasonic cleaning is usually safe, warm soapy water is best. jasper the opaque variety of chalcedony (kal-SED-uh-nee) occurring in shades of many colors and mixtures of the same in various patterns. common sources include the united states, russia and germany among others. ultrasonic cleaning is usually safe, warm soapy water is best. labradorite (LAB-ra-door-ite) a plagioclase feldspar, typically gray to black, but is also found in orange, yellow, red or colorless. pieces which show strong flashes of color, known as labradorescence, are generally used in jewelry. common sources include canada, finland, and russia among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and rough handling. lapis lazuli (LAP-iss LAZH-uh-lee) a conglomeration of minerals, principally lazurite, pyrite and calcite, generally opaque, in shades of blue. a vibrant dark blue with patches of white and golden pyrite is the most prized. dyeing, wax impregnation and oiling are common treatments. common sources include afghanistan, argentina, and chile among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and solvents. malachite (MAL-ah-kite) an opaque, green or bluish-green mineral species usually with banding of alternating light and dark color. wax impregnation is occasionally done to hide small blemishes. malachite occurs in small quantities around the world, generally in copper mining areas, zaire being the most important source. do not use ultrasonic cleaning, warm soapy water is best. avoid heat, solvents and rough handling. moonstone a variety of orthoclase feldspar, semi-transparent to opaque, generally colorless or white with a blue or white sheen, called adularescence, reminiscent of the glow of the moon, sometimes occurring in shades of yellow, peach, brown and gray. common sources include myanmar, sri lanka, and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and rough handling. mother of pearl a variety of shell with the luster of pearl and occasionally with iridescent coloring called orient. dyeing is a common treatment. common sources are the shells of pearl oysters and abalones from the waters around australia, new zealand and the united states. do not use ultrasonic cleaning, warm soapy water is best. avoid heat, solvents and rough handling. obsidian a transparent to opaque natural glass of volcanic origin, in colors of black to gray and brown, and brown to yellow and orange. very rarely in greens, blues and purples. obsidian is sometimes found with the sheen of iridescence. common variety names are snowflake obsidian, rainbow obsidian and apache tears. obsidian is found worldwide. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat and solvents. onyx a variety of chalcedony with straight bands of colors, similar to agate which has curved bands. dyeing and heating are common treatments to produce solid, even coloring or to change coloring. common sources include brazil, uruguay and the united states among other sites worldwide. ultrasonic cleaning is usually safe, warm soapy water is best. avoid excessive heat as color may change. opal transparent to opaque mineral species of amorphous structure with a chemical composition which includes water, 3 to 10% by weight, sometimes up to 20%. opal occurs in any and every body color and generally exhibits the phenomenon, play-of-color, and more rarely the phenomena asterism (star) and chatoyancy (cat's-eye). fire opal is a transparent to semitransparent variety with a yellow, red, orange or brown body color, with or without play-of-color, also called mexican opal. impregnation with smoke, wax, oil or plastic and treatments with dye are common treatments to enhance the color and appearance of the material. australia is the major source for opal, and has been for many years. other sources include brazil and mexico among others. do not use ultrasonic cleaning, warm soapy water is best. opal is very fragile. avoid rough handling, sharp blows, sudden changes in temperature and acids. pearl organic material formed in shellfish, composed of layers of nacre built up around an irritant, known as cultured pearl when man has introduced the irritant. bleaching and dyeing are common treatments to hide blemishes and change coloring. common sources include polynesia, australia, japan and china among others. do not use ultrasonic cleaning, wipe clean with soft cloth. avoid rough handling, heat and chemicals including perfumes and hairsprays. peridot (PEAR-ih-doe) transparent to translucent gem material found in shades of yellowish-green, greenish-yellow and brownish-yellow. peridot is noted for a distinctive "lilypad" type inclusion of liquid and gas. common sources include the united states, china, egypt and brazil among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and chemicals. pietersite a close relative to tiger's-eye (quartz), a sort of petrified asbestos, safe at that, semi-transparent to opaque, with patterns of red, blue, yellow and brown, sometimes with a blue chatoyancy (eye effect). sources are china and namibia. ultrasonic cleaning is usually safe, warm soapy water is best. prehnite a generally translucent material, ranging from pale yellow to brown, often green. this material is usually found in basaltic volcanic rocks, igneous rocks and some in metamorphic rocks. sources are scotland, australia and france. do not use ultrasonic cleaning, warm soapy water is best. avoid heat and chemicals. pyrite an opaque gem material of metallic gold color, sometimes mistaken for gold. common sources include spain, mexico and peru among others. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat and solvents. quartz transparent to opaque gem material appearing in nearly every color imaginable and displaying a variety of phenomena. dyeing, irradiation and heat are fairly common treatments. common sources include brazil, madagascar, mexico and the united states among many others. ultrasonic cleaning is usually safe, warm soapy water is best. rhodochrosite (roe-doe-CROW-site) translucent to opaque, pink gem material, usually with bands of white and red, somewhat reminiscent of bacon. common sources include argentina and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid heat, solvents and rough handling. rhodonite (ROE-duh-nite) translucent to opaque pink to purplish-red gem material with black veining and splotches. rarely, a transparent variety is found. common sources include brazil, mexico, sweden and australia among other locations. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat and solvents. rhyolite (RYE-oh-lite) an opaque, volcanic material composed of quartz and feldspars in shades of greens, browns and white. southwestern united states is a common source, though found worldwide. ultrasonic cleaning is usually safe, warm soapy water is best. riverstone some say a type of jasper, others say a limestone, but opaque and generally in cream tones, with a bit of yellow or pink. found in the united states among other areas. ultrasonic cleaning is usually safe, warm soapy water is best. ruby the transparent to opaque, orange to purplish red and brownish red variety of the mineral species corundum, sometimes displaying the phenomena asterism (star) and rarely, chatoyancy (cat's-eye). heating, oiling and dyeing, diffusion and glass filling are occasional to common treatments performed to enhance the color and appearance of the material. common sources include thailand and sri lanka among others. ultrasonic cleaning is usually safe except for oiled stones, warm soapy water is best. sapphire the transparent to opaque, violetish blue to greenish blue variety of the mineral species corundum, sometimes displaying the phenomena asterism (star), color change from blue to purple, and rarely, chatoyancy (cat's-eye). heating, diffusion and glass filling are occasional to common treatments performed to enhance the color and appearance of the material. common sources include australia, thailand and sri lanka among others. ultrasonic cleaning is usually safe, warm soapy water is best. serpentine semi-transparent to opaque gem material in shades of green and yellow, sometimes with veining of white, brown and black. wax impregnation is common to improve appearance. common sources include new zealand, china and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. sodalite semitransparent to opaque gem material in shades of blue, generally with white veining, and usually a component of lapis lazuli. common sources include canada, brazil and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling. spinel (spin-NEL) transparent to opaque mineral species appearing in shades of red, pink, orange, blue, violet and purple, and rarely displaying the phenomena asterism (star) and color change. also rarely seen are the colors of yellow, green, brown, black and colorless. there are no known treatments, however there is an abundance of synthetic spinel on the market, a common imitation for other gem material rather than being used merely as a synthesized spinel. common sources include myanmar, sri lanka and brazil among others. ultrasonic cleaning is usually safe, warm soapy water is best. spodumene (SPOD-you-mene) transparent mineral species occurring is shades of pink, bluish purple, green, yellow, colorless and very rarely, blue. generally this gem material is light in tone. kunzite is the pink to bluish purple variety of spodumene. hiddenite is the medium green variety, colored by chromium and rarely found. an irradiated green is sometimes found, though rare on account of the color being unstable, and is sometimes referred to, inaccurately, as hiddenite. common sources include brazil, madagascar and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling and abrupt temperature changes. kunzite will fade in light and needs to be stored appropriately. tektite transparent to opaque natural glass in shades of green to brown, thought to be splash products from meteor impacts. moldavite is a transparent to translucent variety of tektite found in shades of yellow and green. moldavite is found in the region of former czechoslovakia, the source for other tektites is southeast asia and australia. ultrasonic cleaning is usually safe, warm soapy water is best. avoid heat and chemicals. tiger iron an opaque conglomeration of tiger's-eye (quartz), jasper (chalcedony) and hematite which has a metallic quality and sometimes a chatoyant appearance (eye effect). the major source is australia. ultrasonic cleaning is usually safe, warm soapy water is best. tiger's-eye a semi-transparent to opaque variety of quartz, generally yellowish-brown (hawk's-eye or zebra tiger's-eye if grayish-blue; cat's-eye if greenish) which displays chatoyancy, the eye effect. the eye effect is caused by inclusions of crocidolite, a blue asbestos, or by quartz which has replaced the crocidolite, following the original fibrous structure. dyeing, bleaching and heat are common treatments which alter the color of the gem material. most tiger's-eye comes from south africa, cat's-eye from sri lanka and india among other locations. ultrasonic cleaning is usually safe, warm soapy water is best. topaz transparent mineral species occurring in shades of yellow, orange, brown, pink, red, purple red, blue, light green and colorless, and rarely exhibiting the phenomenon chatoyancy (cat's-eye). citrine and smoky quartzes and often misrepresented as topaz, topaz being the more expensive gem material. heating and irradiation are common treatments to enhance and/or change the color of the material. common sources include brazil, sri lanka and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling and abrupt temperature changes. a light blow or dropping the stone on a hard surface will damage this gem material. tourmaline (TOUR-ma-leen) transparent to opaque group of mineral species (elbaite, liddicoatite, uvite, dravite, buergerite, olenite, schorl), generally all referred to as tourmaline, appearing in nearly all colors, and very occasionally exhibiting the phenomena, chatoyancy (cat's-eye effect), and color change. irradiation and heat are common treatments which alter the color of the gem material. occasionally chatoyant material will have been treated with acid or with an epoxy filler to enhance the phenomenon. common sources include brazil, russia, madagascar and the united states among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling, especially if parti-colored (the material is most vulnerable where the color bands meet) and sudden changes in heat. avoid chemicals if epoxy filler treatment is known. turquoise semi-translucent to opaque gem material found in shades of blue and green with dark veining and splotches of black, brown or white, commonly found in large stones. impregnation with plastic or wax, dyeing and backing or coating with epoxy are common treatments to alter color, fill inclusions and to add strength. common sources include the united states, iran, mexico and australia among other locations. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling, heat and chemicals. perspiration and cosmetics may alter color. unakite (YOU-na-kite) an opaque conglomeration of green epidote, white quartz and pink feldspar which results in a mottled appearance, sometimes with veining. the source for unakite is the united states. ultrasonic cleaning is usually safe, warm soapy water is best. avoid rough handling and solvents. zircon transparent mineral species occurring in shades of blue, yellow, green, brown, orange, red, colorless and occasionally purple, and rarely exhibiting chatoyancy (cat's-eye). most zircon is in different stages of crystal structure breakdown due to the presence of radioactive elements in its composition, and is classified as high, medium or low type; a.k.a. alpha, beta or gamma. this classification is normally not referred to on the market. zircon is known to be used as a diamond simulant as well as the birthstone for december. heating is a routine treatment to change brown material to most commonly blue. nearly all blue and colorless zircon on the market has been heat treated. common sources include sri lanka, myanmar and thailand among others. do not use ultrasonic cleaning, warm soapy water is best. avoid rough handling, heat and excessive light. heat treated stones may revert to their original color. zoisite (ZOE-ih-site) transparent to opaque mineral species in the epidote group occurring in shades of blue, violet, bluish purple, brown, yellowish green and pink, and rarely exhibiting the phenomenon chatoyancy (cat's-eye). tanzanite is the most well-known variety of zoisite, a transparent blue to violet to bluish purple gem material. ruby in zoisite, a variety also seen, is a translucent to opaque ornamental material with ruby crystals in green zoisite. heating is routine to produce tanzanite from brownish material; nearly all tanzanite on the market has been heat treated. common sources include tanzania (tanzanite), austria and the united states among others. do not use ultrasonic cleaning with tanzanite, though usually safe with other zoisites. warm soapy water is best. avoid rough handling, abrupt temperature changes and acids. references: gemological institute of america, 1995, gem reference guide, gemological institute of america, usa cally hall, 1994, eyewitness handbook of gemstones, 1st american edition, dorling kindersley, inc., new york si and ann frazier, eye on tigereye, lapidaryjournal.com christine woodward and dr. roger harding, 1988, gemstones, sterling publishing co., inc., new york if you love gemstones and want to see some interesting micro-photography, look up this title: e.j. gubelin and j.i. koivula, 1997 third, revised edition, photoatlas of inclusions in gemstones, abc edition, zurich |
copyright © 2004-2010 - sunflower mountain enterprises, llc - powered by Zen Cart