Though sapphires come in different colors, it is most associated with the color of the sea and the sky. In fact, sapphires can be as dark as the ocean depths, or as light as the afternoon skies.
A sapphire is just one of the gemstone varieties of the corundum group, which also includes rubies. Corundum gemstones are especially known for their exceptional hardness, surpassed only by the hardness of a diamond, which is by far the hardest substance on earth.
Since corundum is made of pure aluminum oxide, what contributes to the color of the sapphire is the presence of other elements, such as titanium and iron. Because of these elements, sapphires are able to have many different colors, such as green, blue, pink, and yellow. Whereas all these colored gemstones are still considered sapphires, red corundum are known as rubies. The ruby’s red color is mainly due to chrome mixed with aluminum oxide.
Types of Sapphires The most well-known type of sapphire is the blue sapphire, which is a result of the mixture of titanium and iron with aluminum oxide. Sometimes, the mixture is not well saturated, resulting in a gray shade rather than blue. To enhance its color, these sapphires are “baked” in a temperature of 1800 degrees Centigrade.
Another type of sapphires is the sapphire with fancy colors. As mentioned before, sapphires come in different colors. Purple sapphires are usually cheaper than blue sapphires. To create a purple sapphire, the aluminum oxide is mixed with vanadium. Other sapphire colors include yellow, green, pink, orange and brown. Iron is used to create yellow and green sapphires, while chromium is used to create pink sapphires. Some pink sapphires are even very close to the red color of rubies, and these are priced higher than those with light pink shades. There are also colorless sapphires that are used as a substitute for diamonds. Salmon-colored sapphires are called padparadschas, derived from the Sinhalese word meaning “lotus flower.” They are now a popular collector’s item.
Aside from fancy colored sapphires, there are also color changing sapphires. Just like what its name implies, this type of sapphire appears blue outdoors, while it appears purple indoors. There are also variations, wherein the sapphire appears pinkish under the sun and greenish under fluorescent light. The more evident the color change, the higher the monetary value of the sapphire.
Finally, the star sapphire is so-called because of the six-rayed star found in its center, called as asterism. The asterism phenomenon can be observed under a single bright light source. The value of a star sapphire depends on the carat or the weight of the gemstone. Aside from the carat, its value also depends on the quality of the asterism–its sharpness or intensity, symmetry, body color, and visibility. Some of the famous star sapphires in history are the Star of India, Midnight Star, and Star of Bombay.
There are also synthetic, or manmade, sapphires available in the market nowadays. It was first developed in 1902 by French chemist Auguste Verneuil. Synthetic sapphires can be used in different industrial applications, but they can also be used in jewelry.