Stone Info_Pearls PDF

****PEARLS***** LARGEST CONSUMERS : By 1920, Mikimoto had begun marketing cultured whole pearls internationally. Post World War 11 the first South Sea cultured pearl farm was founded in Western Australia in the 1950s,The first Tahitian cultured pearl farm was started on Manihi Atoll in French Polyne...

****PEARLS***** LARGEST CONSUMERS : By 1920, Mikimoto had begun marketing cultured whole pearls internationally. Post World War 11 the first South Sea cultured pearl farm was founded in Western Australia in the 1950s,The first Tahitian cultured pearl farm was started on Manihi Atoll in French Polynesia in the 1960s, Chinese freshwater cultured pearls appeared on the international pearl market around 1970. Today, consumers buy cultured pearls in chain and independent jewelry stores, discount and warehouse department stores, traditional department stores, through cable TV shopping channels, and via websites. MOHS SCALE: Poor to Good VARIETY/ SPECIES/GROUP : Organic Gem COLOR/HUE RANGE/VALUE: -Akoya: white with rosé overtone and excellent luster, 2 to 11 mm in diameter, with an average size of 6 to 8 mm. (large increase in value from 7 to 7.5 mm and 8 mm) -South Seas: two varieties of P. maxima, gold, cream, yellow, silver in color, soft, satiny luster; gold-lipped and silver-lipped shells, with pearls ranging from 8 to 20 mm, with most falling between 10 and 15 mm. -Tahitain: "Peacock" dark green-gray to blue-gray bodycolor with pink to purple overtones, "Aubergine" is dark grayish purple bodycolor. "Pistachio " yellowish green to greenish yellow bodycolor. 8 mm to 17 mm, with most falling between 9 mm and 14 mm -Fresh Water: colors that include creamy white, lavender to purple, pink, orange, blue, and golden, round and near round, range from 4 to 14 mm (larger can be above 19mm) -Non-nacreous Pearls: Conch Pearls - pink and are rarely spherical. Most are oval or irregular in shape, with lengthwise dimensions almost always under 10 mm. Melo Pearls- Orange, large and spherical & between 20 and 30 mm in diameter - All pearls display bodycolor, but only some show overtone or orient or both. GIA Body Color Descriptions: -Neutrals—white, gray, and black -Near-neutrals—silver, cream, and brown -Hues—all other (fancy) colors CHEMICAL COMPOSTION: Nacre: microscopic platelets of aragonite, crystallized form of calcium carbonate, a chemical compound of calcium, carbon, and oxygen, Nacre also contains conchiolin -Non-nacreous Pearls: aragonite crystals are arranged in columns that are mostly perpendicular to the pearl’s surface. Not all non-nacreous pearls have this_but those that don't are called “porcelaneous. Nacre Quality Grading: Acceptable—Nucleus not noticeable; no chalky appearance Nucleus Visible—The cultured pearl shows evidence of its bead nucleus through the nacre Chalky Appearance—The cultured pearl has a dull appearance FORMING SOURCE : - Akoya Saltwater pearls from the " Pinctada fucata" or "Pinctada chemnitzii" oyster - South Sea pearls from "Pinctada maxima" oyster, can be nucleated up to three times with the third nucleation producing the largest cultured pearl - Tahitian Pearls from "Pinctada margaritifera" oyster - Fresh Water Pearls from "Hyriopsis cumingii" (triangle mussel) or "Hyriopsis schlegelii" (Biwa mussel), hybrid of both "Leisure mussel", Soufflé pearls are large, lightweight baroque Chinese freshwater cultured pearls with high luster and a wide color range with11 mm to 14 mm diameter - Non-nacreous Pearls: Queen conch, "Strombus gigas" (snail shell) Melo Pearls come from the Melo Melo Sea snail CRYSTAL STRUCTURE: three basic methods to produce whole freshwater cultured pearls: mantle tissue nucleation, second-generation production, and coin-bead/spherical-bead (CBSB) production. POSSIBLE PHENOMENA: Flame Structure (Orange melo pearls can exhibit distinct flame structure) Overtone: is one or more translucent colors that lie over a pearl's bodycolor Orient: increases value for it’s beautiful, usually indicates thick, high-quality nacre. And third, it’s rare and desirable. Luster: Luster in pearls is caused by light traveling through translucent layers of nacre and reflecting back to the eye. CLARIETY CHARACTERISTICS (Surface Texture): Nacre Grading: Thickness, Translucence, Layer uniformity, Layer alignment Luster: Excellent—Reflections are bright, sharp, and distinct Very Good—Reflections appear bright and near-sharp Good—Reflections are bright but not sharp and slightly hazy around the edges Fair—Reflections are weak and blurred Poor—Reflections are dim and diffused Blemishes Abrasion—A series of scratches on the surface of a pearl Bump—An irregular bulge, blister, or welt, usually too small to affect basic shape Chip—An opening or cavity in the surface Crack—A surface-reaching break or fracture in the nacre, or a break or fracture in the nucleus Flat—A flat section on an otherwise spherical pearl, usually too small to affect basic shape Gap—An area where the nacre has not covered the nucleus Pit—An indentation or depression, found individually or in a group Scratch—A thin groove or depression in the surface Spot—An area that is darker, lighter, or more dull than the surrounding nacre Wrinkle—An irregular ridge or crease on the surface Blemishing Grading: Clean—Pearls can be blemish-free (spotless) or contain minute blemishes that are very difficult to see when examined by a trained observer Lightly Spotted—Pearls show minor surface irregularities when examined by a trained observer Moderately Spotted—Pearls show noticeable blemishes Heavily Spotted—Pearls show obvious surface irregularities that might affect durability Nacre Quality Grading: Acceptable—Nucleus not noticeable; no chalky appearance Nucleus Visible—The cultured pearl shows evidence of its bead nucleus through the nacre Chalky Appearance—The cultured pearl has a dull appearance TRADE NAMES : South Sea "Golden Lipped Oyster" or Silver Lipped Tahitian - "Black Lipped Oyster", "Peacock", "Aubergine", "Pistachio" Fresh Water - "Edison Pearls" ( higher quality then souffle pearls) or "Fire Balls" Apricot—Light pinkish orange Chinese freshwater cultured pearls Aubergine—Tahitian cultured pearls with a dark grayish purple bodycolor Golden—Strong greenish yellow to orangy yellow South Sea cultured pearls Lavender—Light pinkish purple Chinese freshwater cultured pearls Peacock—Tahitian cultured pearls with a dark green-gray to blue-gray bodycolor and rosé to purple overtones Pistachio—Tahitian cultured pearls with a yellowish green to greenish yellow bodycolor COUNTRIES OF ORIGIN : natural pearls were farmed off the Persian Gulf, Akoya cultured pearls are produced in Japan, China, and Vietnam, Korea, Southeast Asia, Australia, the Red and Mediterranean seas, the Persian Gulf, the South and East African coasts, and the Caribbean. South Sea cultured pearls are produced principally in Australia, Indonesia, the Philippines, and Myanmar TahitianFrench Polynesia and the Cook Islands produce commercial quantities of Tahitian cultured pearls Fresh Water pearl in China Queen conch or"Strombus gigas" (snail shell)are found in the Caribbean Sea, Melo Pearls are found in Southeast Asia and Australia, COMMON TREATMENTS: Luster EnchancementDyeing - inorganic dye is silver nitrate, Tinting-noticeable at drill hole with a concentration of color Irridiation-after treatment, the irradiation-darkened bead nucleus Silicone polymer coatings Filling- Filler materials include wax, resin, metal wires, and even other cultured pearls. Peeling- the careful remove of layers of nacre, specialized treatment of South Sea and Tahitian cultured pearls COMMON CUTS (shapes) : Spherical: Round or Nearly Round, Symmetrical: Oval Button or Drop, Baroque: Semi- Baroque, Baroque -Size is measured in mm, spherical pearls, the diameter is measured. For other shapes, the length and width are measured. Tahitian- round, near round, baroque Fresh Water - round and nearly round MAIN SYNTHETIC PROCESS: Cultured pearls are type in this case COMMON IMITATION MATERIAL: Essence'd Orient: a mixture of iridescent fish scales and varnish used to coat glass beads, plastic, mollusk shell CUTTIG/TRADING CENTER: Processors are most prominent in Japan and China, Manufactures buy from processors or dealers or directly form the farmers Dealers sell to retailers and manufactures, Dealers buy directly from the farmer, other dealers, cooperative marketplaces, or at an auction. Auctions take place in Tahiti, Hong Kong, Japan, and Australia. Some of the auctions are by invitation only. Online sales happen with dealers in Tokyo to Hong Kong MORE INFO: Post Harvest Prodcures: Sorting- color, size, amount of blemishes Drilling and cutting- full or half, or make three-quarter-cut pearls (to hide or remove blemishes) Bleaching- used widely so not considered a treatment Buffing- walnut shells or ground corn cobs with wax; tumbled or vibrated Matching and stringing- Strung within one-half millimeter of each other in diameter, strung on silk or nylon with 5 or more 14" or 16" strands make a "hatch" Match Grading : Excellent—Pearls are uniform in appearance and, if drilled, drilled on center Very Good—Very minor variations in uniformity Good—Minor variations in uniformity Fair—Noticeable variations in uniformity Poor—Very noticeable variations in uniformity Extra Info: Natural Blister Pearl: Natural blister pearls form in saltwater and freshwater mollusks in a way that’s very similar to natural whole pearl formation. The formation process is the same but the pearl adheres to the side of the shell Mabe Pearls: A mabe (MAH-bay) is an assembled cultured blister pearl. A mabe pearl is a three-part assembly consisting of a nacre dome, a filler, and a mother-of-pearl backing. Pinctada maxima, Pteria penguin (teh-REE-uh PEN-gwin), and Pteria sterna (teh-REE-uh STUR-nuh) mollusks to create these pearls. Mabe pearls might appear in symmetrical dome, drop, and heart shapes. Abalone Pearls: Can be whole body pearls or blister pearls, majority of natural whole abalone pearls are irregularly shaped, they are senstive and can bleed to death if injured and only have one shell so they are pron to injury make their pearls valuable at large sizes Keshi Pearls: Keshi are accidental byproducts of the pearl culturing process, usually small, baroque in shape, richly colorful, and highly lustrous. Seed Pearls: Seed pearls are very small natural pearls produced by both saltwater and freshwater mollusks,can be round, near-round, or irregular in shape, less than 2 mm in diameter, jewelry makers used horsehair to string them because silk was too thick.