Sapphire precious gemstone index and mineral information

Any color of corundum other than red is called sapphire. Sapphire’s name derives from the Greek “blue.” Sapphires can be blue, black, purple, violet, dark blue, bright blue, light blue, green, yellow, and orange. Colorless sapphire is called leuko-sapphire, name deriving from the Greek “white;” pinkish orange sapphire called Padparadscha, which is a Sinhalese word meaning “lotus flower;” and sapphire that appears blue in daylight and reddish or violet in artificial light is called alexandrine or alexandrite sapphire. Blue sapphires get their blue color from traces of titanium and iron; the red hues are due to chromium, and the violet stones, vanadium.

Since the middle ages sapphire was understood to mean what is today known as lapis lazuli. Since 1800 the sapphire and ruby are recognized to be a gem variety of corundum. Pure cornflower-blue is the most desired color in a sapphire. Sapphire is also a rough stone as the ruby. It also has no cleavage, but has certain preferred directions of parting as the ruby.

The host rocks for sapphire are dolomotized limestones, marble, basalt, or pegmatite. It is mined mainly from alluvial deposits or deposits formed by weathering, rarely from the primary rock. Sapphire is often parti-colored, meaning one part is blue and the rest is colorless. Stones are usually faceted as mixed cut gems. Star-stones are cut en cabochon.

Non-gemstone corundum is used as an abrasive for grinding optical glass and for polishing metals, and has been made into sandpapers and grinding wheels; when naturally mixed with magnetite, it forms emery. As with ruby, sapphire has been synthesized in industrial quantities since the 1920s, and it has replaced the natural material in most applications.

Ancient Greeks believed that sapphires cured eye diseases and set prisoners free. Medieval alchemists believed sapphires related to the element air and that it was an antidote for poisons and had the power to influence the spirits. In the East, sapphire is regarded as a powerful charm against the evil eye.

Blue sapphire looks similar to benitoite, indicolite, iolite, kyanite, spinel, tanzanite, topaz, and zircon, as well as blue glass.

Sapphire is one of the twelve gemstones of the ceremonial breastplate worn by the high priest Aaron, representing the twelve tribes of Israel as described in the Old Testament book of Exodus, and is also known as the month of September’s birthstone meaning, clear thinking.

Mohs’ hardness: 9