Stone Info_Ruby.pdf

** Ruby ** LARGEST CONSUMERS : US, China, Japan, the European Union, and—for high-end stones—the Middle East and auctions in Switzerland. MOHS SCALE: 9 VARIETY/ SPECIES/GROUP : Species: Corundum COLOR/HUE RANGE/VALUE : range from orangy red to purplish red, finest ruby has a pure, vibrant red to...

** Ruby ** LARGEST CONSUMERS : US, China, Japan, the European Union, and—for high-end stones—the Middle East and auctions in Switzerland. MOHS SCALE: 9 VARIETY/ SPECIES/GROUP : Species: Corundum COLOR/HUE RANGE/VALUE : range from orangy red to purplish red, finest ruby has a pure, vibrant red to slightly purplish red hue, vivid saturation, and medium to medium dark tone CHEMICAL COMPOSITION: forms in environment with low silicon content, aluminum oxide, a mixture of aluminum and oxygen, part of the metamorphic process FORMING SOURCE : Finest rubies have trace elements- Chromium, the more chromium the saturated the hue, chromium is can also cause fluorescence, finest ruby forms in marble, but also found in alkali- basalt host rocks with trace elements of iron(darker rubies), Metasomatism process which minerals exchange their chemical components in the presence of fluids. Desilication, a process that removes silicon from the rock, leaving aluminum and oxygen behind to form corundum, mined from secondary deposits CRYSTAL STRUCTURE : tabular hexagonal prism, elongated prisms and bipyramids. POSSIBLE PHENOMENA: Pleochroism CLARITY CHARACTERISTICS : silk (rutile needles), boehmite needles, included crystals, fingerprint inclusions, growth zoning, color zoning, and color banding COMMON TREATMENTS : almost all rubies are heat treated (removing blue and brown) to develop or intensify a ruby’s color, remove or decrease banding or zoning, or reduce modifying hues, fracture filling with lead glass, dyeing with colored oils, and filling small surface-reaching fractures with epoxies, surface coating, flux healing and lattice diffusion COMMON CUTS : most commonly fashioned as ovals and cushions with brilliant-cut crowns and step- cut pavilions, Round, trillion, emerald-cut, pear, and marquise rubies are also available, Cutters can minimize the orangy red color by orienting the table facet perpendicular to the crystal’s optic axis TRADE NAMES : “pigeon’s blood”, “Burmese " or “Burmese color” representing the finest rubies from Mogok region of Myanmar, “Thai” and “Pailin” describe rubies that look similar to that area,generally have a brownish red to purplish red hue with black extinction areas, making them appear darker than Burmese stones, “crimson” rubies are rich, slightly purplish red, and “scarlet” rubies are red with a slight hint of orange COUNTRIES OF ORIGIN : Finest ruby are found in Montepuez area of Mozambique, Myanmar, Afghanistan, and northern Vietnam, Thailand and Cambodia, southern India, Kenya, Sri Lanka, Tanzania, and central Vietnam,Madagascar, Malawi MAIN SYNTHETICS PROCESS : Verneuil or flame-fusion method, melt and solution processes COMMON IMITATION MATERIALS: glass—often backed with colored coatings or foil, Natural spinel and red garnet,synthetic spinel and synthetic cubic zirconia, quartz, doublets CUTTING/ TRADE CENTER: Thailand is considered ruby’s major cutting, treatment, and wholesale trading center. Other important ruby centers include Jaipur, India; Sri Lanka; and China’s Guangdong Province