Heating often improves the color and clarity of the gem. Stones, generally before they are cut, are heated to between 1700 to 1800 degrees Celsius (3100-3300 degrees F) for several hours. The most common treatment for star sapphire is heat treatment. Malawi, Nigeria, Pakistan, Rwanda, Tanzania, United States (Montana), Vietnam and Zimbabwe. Other significant star deposits are in Brazil, Cambodia, China, Kenya, Madagascar. The most important deposits today are in Australia, Myanmar, Sri Lanka and Thailand. One should look for an even roundness to the shape. The best cabochons are somewhat transparent, with smooth domes of good symmetry. Less transparent sapphires, translucent or opaque stones, are cut en cabochon to support the star effect with its six rays. Included rutile needles cause the star effect. The six-rayed-star light effect appears most clearly under natural light. The most desirable color is a vivid, intense blue. A small iron content only results in yellow and green tones, chromium produces pink, iron and vanadium orange tones. The coloring agents in blue sapphire are iron and titanium and, in violet stones, vanadium. Star sapphire range in color from blue in various tones, to pink, orange, yellow, green, lavender and gray to black. In ancient times, star sapphire was regarded as a powerful talisman guiding travelers and seekers of all kinds. Star sapphire is a durable, popular stone for men's rings. Star sapphire range in color from blue in various tones, to pink, orange, yellow, green, lavender, gray to black. Aligned needles that intersect each other at varying angles produce a phenomenon called asterism. Star sapphires contain unusual tiny needle-like inclusions of rutile. Corundum is the second hardest substance on the Mohs scale, with a rating of 9. Red corundum is called ruby, all other color varieties of corundum being referred to as sapphire. Star sapphire is a member of the corundum family.
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