Essential notes on precious stones
Sapphire, September's birthstone, has been the pre-eminent blue gemstone for centuries. Ancient Persian rulers believed its reflection painted the heavens blue. Indeed, its very name in Latin, sapphirus, means blue.
While Sapphire has become the ultimate blue stone, color given by steel and titan contents, it actually comes in virtually every color except red (red Sapphires are Rubies), including colorless (do not be mistaken with diamonds) and white, and such fancy colors as yellow (less steel contained), peach, orange, cognac, pink, violet, purple and green and all their many shades. In fact, white Sapphire has become a popular natural Diamond substitute for many people. Moreover fancy color Sapphire often provides an alternative to other gems in similar colors that are less durable.
It is considered the most important and versatile of the gem families. Although Sapphire is not as brilliant as diamond, it has striking luster. Sapphires can be cut in as many shapes as diamonds. Additionally, like Ruby, Sapphire may be found in a translucent variety that may display a six-rayed star effect when cut into a cabochon (dome) shape. This type is known as star Sapphire, of which there are numerous synthetics on the market. Also, another unique quality of some Sapphires, next to some Rubies as well, is the appearance to change slightly its color when it's viewed from different angles and the light is coming in different angles too versus the stone table.
Natural gem-quality sapphire is found in many parts of the world, but the rarest gems are from Kashmir and Myanmar (Burma), most prized because their color is closest to pure spectral blue. Fine Sapphire is also produced in Sri Lanka in limited supply, both in blue and fancy color. Sapphire is also found in Thailand, Cambodia, Tanzania, Madagascar, Australia and the United States (Montana). Perfect natural gems in color and appearance are very rare and expensive.
Controlled heating is commonly used in the trade to produce, intensify or lighten color and/or improve clarity in many gems including blue and fancy sapphire. This allows the trade to bring more, better quality gems to the market. Heat enhancement is permanent and stable, but in such cases the jewelers has to inform their customers and to mention this aspect in the stone certificate.
Sapphire, sister to Ruby, is known in the mineral world as corundum, which is a hexagonal crystal structure composed of aluminum oxide. On the Mohs scale of hardness, Sapphire ranks 9, the highest in the gem world after diamond. It is considered very durable, a great choice for rings and bracelets that are prone to knocks.