Stone Info_Tanzanite & More PDF

****Tanzanite, Iolite, Chrysoberyl, and Andalusite***** LARGEST CONSUMERS : Tanzanite: named and promoted by Tiffany's in 1968, government control of the mine made prizes fluctuated, tv promoted it to US consumers, Alexandrite: Asia Cat's Eye: Asia MOHS SCALE: Tanzanite: 6 to 7, Iodite: 7 to 7.5, Al...

****Tanzanite, Iolite, Chrysoberyl, and Andalusite***** LARGEST CONSUMERS : Tanzanite: named and promoted by Tiffany's in 1968, government control of the mine made prizes fluctuated, tv promoted it to US consumers, Alexandrite: Asia Cat's Eye: Asia MOHS SCALE: Tanzanite: 6 to 7, Iodite: 7 to 7.5, Alexandrite: 8.5, Andalusite: 7 to 7.5 VARIETY/SPECIES/GROUP: Tanzanite: variety of zoisite Alexandrite: variety of chrysoberyl Cat's Eye: chrysoberyl ,previously called "Cymophane" COLOR/HUE RANGE/VALUE: Tanzanite: Fine quality is pure blue, intense violet-blue, violet bodycolor or strong purplish pleochroic (pale or grayish colors) -Other Zoisites: opaque green zoisite,Ruby-in-zoisite, translucent-to-opaque pink zoisite is streaked or mottled with gray or white, is called thulite, green-blue, golden, sometimes marketed as fancy-color tanzanites Iodite: also know as "Cordierite" a transparent, violetish blue through violet hue, pheochroic colors range from light/dark violet to yellow/yellow-brown and blue gray Alexandrite: very strongly bluish green through yellowish green in daylight, and orangy red through purplered in incandescent light, medium to medium-dark tone and moderately strong saturation, hue only changes due to the "Alexandrite Effect" tone & saturation stay the same Cat's Eye: the chatoyant band is distinct, straight, and silver-white, fine quality is a semitransparent golden yellow to slightly greenish yellow or a brownish yellow “honey” color Yellow Chrysoberyl: transparent greenish yellow chrysoberyl with no chatoyancy, formally called "chrysolite" Green Chrysoberyl: green nonphenomenal chrysoberyl named “mint chrysoberyl",colored by traces of vanadium Andalusite: brownish or yellowish green to orangy brown, can also be pure green, brown, pink, or violet, finest quality is yellowish green and orange - "Chiastolite" : andalusite also occurs as an opaque material with a distinctive cross-shaped marking against an opaque white, gray, greenish, reddish, or light brown background CHEMICAL COMPOSTION: Tanzanite: silica, calcium, an aluminum Iodite: ilicate of aluminum, iron, and magnesium, trace element of iron Alexandrite: mostly of beryllium aluminum oxide, trace elements of chromium Andalusite: aluminum silicate FORMING SOURCE: Iolite: alluvial deposits, Alexandrite: alluvial deposits, Andalusite: trace elements of iron and titanium POSSIBLE PHENOMENA: Tanzanite: pleochroism, Iolite: pleochroism, Alexandrite: color change or “the alexandrite effect” and cat's eye Cat’s-Eye Chrysoberyl: chatoyant, also pleochroic Anadalusite: pleochroic colors tend toward reds, greens, and oranges,also hues of olive or brownish green, yellowish green, and brownish red CLARIETY CHARACTERISTIC: Tanzanite: one direction of cleavage & sensitive to thermal shock Iodite: Cleavage in one direction making it vulnerable when mounted Cat's Eye: parallel needles or hollow tubes(typically rutile) Chiastolite: carbon inclusions that form the imprint of a dark cross COMMON TREATMENTS: Tanzanite: 95 percent of blue tanzanites are heat treated to turn the brown stone to blues and violets Iotite: never treated COMMON CUTS: Tanzanite: faceted oval mixed cut, cushion shape, octagon, or trillion Iodite: cabochons, but mainly faceted 1 to 10 cts., but fine gems over 5 cts. are rare Alexandrite: faceted mixed cut, always cut to show best color change Cat's Eye: Cabochon with inclusions running the length of the base, fine quality runs girdle to girdle, even proportions, no extra weight at or below the girdle, typically 0.50 to 2.00 cts., stones up to 170 cts. exist Andalusite: faceted, Sizes range from 1 to 10 cts. - Chiastolite: cabochon or tablet, amulets and charms TRADES NAMES: Alexandrite: “emerald by day, ruby by night” Cat's Eye: Greek for "wavelike form", “milk and honey” effect CRYSTAL STRUCTURE: n/a COUNTRIES OF ORIGIN: Tanzanite: Merelani in northern Africa near Tanzania Iolite: Sri Lanka, several areas of Africa, Kenya, central Tanzania, and the island of Madagascar, India, Brazil, Norway, and Finland Alexandrite: Ural Mountains of Russia, Sir Lanka, Lavra de Hematita area of brazil at the Minas Gerais,India, Myanmar’s Mogok Stone Tract, East Africa, and Madagascar Cat's Eye: Sir Lanka, Brazil, Myanmar’s Mogok Stone Tract, Zimbabwe, Madagascar, and Tanzania Non-Phenomenal Chrysoberyl: Sir Lanka Andalusite: Brazil, Sri Lanka, and Spain, Brazilian andalusite shows the best hues, including a dark green bodycolor and a rare rose-red bodycolor -Chiastolite: Siberia, South Australia, Myanmar, Zimbabwe, and the US states of Arizona and California MAIN SYNTHETIC PROCESS: Tanzanite: Synthetic forsterite is actually used as synthetic tanzanite because of its pleophroic qualities, "Coranite" bluish synthetic corundum, glass, "Tanavyte" purple synthetic YAG Alexandrite: "Czochralski", floating zone, and flux, Japan’s Kyocera Corporation was the first to produce a commercially available synthetic cat’s-eye color-change alexandrite Green Chrysoberyl: vanadium is used to produce bluish green, nonphenomenal, pulled synthetic chrysoberyl. COMMON IMITATION MATERIAL: Tanzanite: glass Alexandrite: Synthetic corundum and synthetic spinel, quartz-An assembled two layers of rock crystal quartz with dyed filter produces the color change Cat's Eye: cat's-eye quartz, yellow cat's-eye tourmaline, bleached tiger's-eye quartz and cat's-eye glass CUTTING/TRADING CENTER: Tanzanite: Jaipur, India, cutting & faceting is also done in Tanzania