Rubies can range in color from pinkish red to orangey, purplish and brownish-red, depending on their chromium and iron content. Ruby gets its name from the Latin word 'ruber', which means red. Owing to its superior hardness combined with its rich color and silky shine, fine quality ruby is classed as one of the group of four so-called "precious" stones, along with diamond, emerald and sapphire. Corundum is the second hardest mineral on the Mohs scale, with a hardness rating of nine. Ruby is classified as the red form of gem-quality corundum all other color varieties of corundum are referred to as sapphire. In rough form, ruby is dull and greasy, but when cut and polished its luster is comparable to fine diamond. It is the rutile which is responsible for its silky shine. The star effect is owed to aligned needle-like rutile inclusions. Star ruby is a rare variety of ruby that exhibits asterism a six-rayed star that shimmers over the surface of the stone when it is moved. About Star Ruby - History and Introduction
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