Sapphire is the official birthstone for the month of September as adopted by the American National Association of Jewelers in 1912. It is also one of the birth stones for the Zodiac signs of Pisces, Taurus, Virgo and Sagittarius. Sapphire is gifted as a gem for the 5th, 23rd and 45th wedding anniversaries while a star sapphire is gifted on the 65th wedding anniversary.
Sapphire is the non-red variety of corundum (the red variety of corundum is ruby). The name corundum comes from the ancient Sanskrit "kuruvindam", while the name "Sapphire" comes from the Persian word "safir", meaning "beloved of Saturn", (or Greek sapphiros).With hardness of 9 on the Mohs scale of hardness, sapphire is the second hardest natural mineral. It is noted in several texts that sapphire was the lapis lazuli of the ancient world, probably because the stones both have the same intense blue coloring.
Blue is by far the most popular color for sapphires, but they can be almost any color, including yellow, green, white, colorless, pink, orange, brown, and purple. Padparadscha is the name for a rare orange-pink variety of sapphire and has a higher value than blue sapphires.
Sapphires with inclusions of tiny, rutile needles exhibit an optical property called asterism. This is the star shaped effect seen in star sapphires and is usually only seen in cabochon cuts.
Star sapphires usually have six ray stars, but twelve ray stars are also known. Rarely, when sapphires are cut en cabochon, they can demonstrate a cat's eye effect. This effect displays a thin band of light down the center of the stone and is known as chatoyancy.
Heating colorless and very pale blue sapphires to high temperatures is done to give them an intense blue color This treatment can also improve the clarity of the stones by removing tiny inclusions.
A rare variety of sapphire, known as color changing sapphire, exhibits different colors in different light. A color change sapphire is blue in natural light, and violet in artificial light. A similar effect is also seen in alexandrite.
Sapphire was first created synthetically in 1902 and is hard to distinguish from natural sapphires except by gemologists. Lab grown sapphires range in price and smaller stones are frequently used in less expensive jewelry.
Sapphire is mined in Australia, Sri Lanka and Thailand. Other producers are Burma, Kampuchea, Kenya and Tanzania. Sapphires are commonly heated to improve their color and reduce cloudiness that is caused by rutile inclusions. The rutile inclusions are responsible for the "star" or "cat's eye" in star sapphires.
Sapphire - Important Characteristics
Hardness (Mohs Scale)
Atomic (Crystal )Structure
Index of Refraction
:3.99 - 4.10
:Vitreous to semi-transparent
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