Sapphires are considered one of the “Big 3” precious gems and often command some of the highest prices per carat in fine qualities. Over 95% of sapphires are heated to improve their color. Natural, unheated sapphires are more rare, and more valuable, than heated sapphires of the same quality.
Sapphire is a 9 out of 10 on the Mohs Scale of Hardness, second only to diamond. In addition to their beauty, sapphire's resistance to scratching is another reason why it's such a popular gem. Although historically the most valuable sapphires have been mined in Kashmir, many other locations have produced very fine quality, beautiful, and valuable sapphires. Several of these locations include Sri Lanka (Ceylon), Burma (Myanmar), and even Montana (United States).