Ruby Information PDF
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Uploaded by ComplementaryLutetium
Gemological Institute of America
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Summary
This document provides information about rubies, including their properties, such as their color range and Mohs scale rating. It also describes the different sources of rubies, the trade centers, and the countries where rubies are most commonly found.
Full Transcript
** 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
