VIEWS: 369 PAGES: 29 POSTED ON: 12/11/2010
PEARLS Jodie Diegel, GG, MBA Graduate Gemologist Gemological Institute of America PEARLS The Product Types of Pearls Farming Cultured Pearls Making Bead Nuclei Nucleating the Oyster Farming Cultured Pearls Raising Production Stock Harvesting Cultures Pearls Processing Cultured Pearls Judging Pearl Value Factors The Product Pearls are classified by gemologists as cultured stones. They are not “inorganic” as most stones are but “organic” They come from an animal or plant Other examples includes amber, coral, ivory and jet The Product Natural Pearls Cultured Pearls Saltwater Freshwater Fewer than 20 species of the 8,000 mollusks produce pearls The Product The world’s main pearling grounds were depleted in the 18th century due to constant demand By the beginning of the twentieth century most of the world’s pearl-producing mollusks were in immediate danger of extinction The Product Pearls are made of NACRE A natural substance produced by mollusks that also costs the inside of the animal’s shell (also called “mother of pearl”) Nacre is made up mostly of calcium carbonate in the form of the mineral aragonite and held together by crystal layers called conchiolin The Product Natural Pearls Parasitic Invasion Mollusk forms a sac around the intruder and secretes nacre from the mantle tissue (the layer of tissue that surrounds the body of the mollusk and lines the shell) Cultured Pearls Human assistance w/bead or tissue nucleation Nacre secreted around bead or mantle tissue Beads for saltwater oysters Tissue for freshwater Fewer than 20 species of the 8,000 mollusks produce pearls (also “keshi” pearls) The Product Pinctada fucata “Akoya” Mostly found in Japan White/cream/yellow “Mikimoto” Pearls usually 2-11mm in size, majority 6-7 mm Usually spherical preferred Approximately 2000 pearl farms in Japan The Product Pinctada maxima “South Sea” Australia, Philippines, Indonesia Largest size yellow/silver Often 9-20 mm with the majority about 13 mm The Product Pinctada margaritifera “Tahitian” French Polynesia (Tahiti) Black/silver Spherical generally range in size from 8-13 mm Often black hue but different tones Farming Cultured Pearls Natural supply has depleted over centuries Need highly trained technician and mantle tissue Making Bead Nuclei Beads often come from freshwater shells from US Need minimum sizes to keep mussels American Pearl Company Nucleating the Oyster 2 types of nucleation Bead Tissue When nucleated: Slow metabolism Careful opening (Tahitian and South Sea can be re-nucleated) Add Tissue and/or bead nucleus Freshwater usually tissue alone (no bead) Farming Cultured Pearls Pearls Farms Small family farms Large commercial/sophisticated operations Problems/Challenges Pollution Severe weather (drought/flooding) Red Tide Raising Production Stock Collecting from wild More labor intensive Divers Hatcheries More controlled but size limited “Spat” collection Especially Tahitians Harvesting Cultured Pearls Every 2-3 months mollusks cleaned Harvesting: 8-24 months Akoya 2 years Tahitian/South Sea 2-6 years Freshwater Harvesting Cultured Pearls Only South Sea and Tahitian are kept alive and can be nucleated again Subsequent pearls are LARGER! Freshwater may be once more Akoya can have up to 5 beads Freshwater can hold up to 50 pieces of mantle tissue Processing Cultured Pearls Bleaching Dyes Sorting Size, shape, luster, surface quality, matching ability Drilling Full (necklaces) Half (earrings, posts) Judging Pearl Quality There are 7 features that directly affect a cultured pearl’s beauty and value Collectively called “VALUE FACTORS” Understanding these will give you the product knowledge to help recognize the beauty and rarity of all pearl types Judging Pearl Quality 1. SIZE A pearl’s ultimate size can depend on many variables Size and health of the mollusk Size of the nucleus Amount of time in the water adding layers of nacre Larger pearls usually more valuable Judging Pearl Quality 2. SHAPE While round is perhaps the most familiar shape, pearls come in many different forms. Spherical, Symmetrical, Ovals, buttons, drops, baroque Judging Pearl Quality 3. COLOR A pearl’s color is made up of Hue-the color’s first impression Tone-its lightness or darkness Saturation-its strength or intensity GIA recognizes 19 pearl hues Judging Pearl Quality 4. LUSTER “The true magic of a pearl lies in its luster” and how it reflects light Luster is the most important of all of the value factors to the beauty of a pearl. 4 categories: Excellent-reflections bright, sharp, distinct Good-bright reflections but not sharp Fair-weak and hazy Poor-dim, no reflections Judging Pearl Quality 5. SURFACE QUALITY Cultured pearls are organic so it isn’t surprising when they show surface characteristics. Abrasions, bump, chips, cracks, gaps, pit, scratches, spots or wrinkles Categories: Clean Lightly blemished Moderately blemished Heavily blemished Judging Pearl Quality 6. NACRE QUALITY Nacre is the very essence of the pearl itself A pearl’s appearance helps determine its quality and it has a LOT to do with whether the nacre is thick or thin (thin=“blinking”) Classifications: Acceptable Nucleus Visible Chalky Appearance Judging Pearl Quality 7. MATCHING The matching value factor is relative (only applies to strands, or jewelry with more than one pearl) Classifications: Excellent Good Fair CONCLUSION Pearls have been and are forever fashionable, and were revered in Asia since approx. 4000BC With the advent of culturing, new and exciting pearls have become available in the last century More affordable due to great influx of freshwater pearls CONCLUSION Pearls invoke words such as Purity Devotion Love Rarity Romance Elegance CONCLUSION QUESTIONS? QUESTIONS?
Pages to are hidden for
"PEARLS"Please download to view full document