Sapphires are precious gemstones primarily composed of corundum, typically known for their deep blue hue, although they can come in various colors except red (red corundum is classified as a ruby). They are valued for their beauty, durability, and rarity.
They have a hardness of 9 on the Mohs’ scale making them the second most durable gemstone to Diamond. The most valuable stones are deep blue with a clarity and a lustre all of their own. Rare varieties do occur and colour changing sapphires are highly desirable as they magically change colour in different lights.
The birthstone for September, the zodiac stone for Taurus and the 45th anniversary gemstone make Sapphires a popular choice.
Most sapphires have been exposed to heat, either naturally in the Earth's crust or by man, which can enhance their clarity and is an acceptable process. A sapphire which displays an inclusion or a type of mineral which would have been destroyed during a heat process makes a rare stone indeed. Usually certificated, these stones may be highly valuable.