Among the natural gems only diamonds are harder than rubies. Rubies have a hardness of 9.0 on the Mohs scale of mineral hardness and diamond has 10.0.
The rubies contain impurities naturally. The impurities includes rutile needles known as “silk”. Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, simulants, or substitutes
Myanmar (Burma), Thailand, Sri Lanka, Tanzania, Kenya, Madagascar, and Cambodia are the places where rubies are mined, but they have also been found in the U.S, in Montana, North Carolina and South Carolina. The Mogok Valley in Upper Myanmar has produced some of the finest rubies, but in recent years very few good rubies have been found there.
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