Blue Sapphire: September Birthstone

Blue sapphire is considered a primary color gemstone; the purer the primary hue, the more valuable the gemstone. Named from the Greek word sappheiros meaning blue, sapphires have been highly priced gemstones since 800 BC. Rulers of ancient Persia believed the sky was painted blue by their reflections and in the antiquity, kings and queens thought that blue sapphires protected their owners from envy and harm.

Sapphire is the birthstone for September and the zodiac gemstone for Taurus. Sapphires belong to the same mineral species as rubies, called corundum. Except for Red Corundum, which is Ruby, all other colors of Corundum are Sapphires. . Blue is considered Sapphire’s “true” color and the one most often recognized. Sapphires also come in violet, dark gray, orange, yellow, pink, green and black, which tends to be relatively inexpensive. These different colored sapphires are referred to as “fancy sapphires” and are often less expensive than the blue ones, yet equally as beautiful and a fine alternative to blue. A rare colored kind of sapphire is called “Padparadscha,” which means “Lotus color.” It is the only color sapphire given its own name besides the ruby. This stone is orange and pink simultaneously and can be very expensive. 

Blue Sapphires hold their blue color from the combination of two chemical elements, iron and titanium. Blue Sapphire ranges in hue from pale to deep azure or dark royal blue, to indigo, with the most highly desired color being the velvety cornflower blue, also called Kashmir or bleu de roi. Burma and Sri Lanka have beautiful sapphires too. They are also found in Thailand, Cambodia, Australia and East African countries like Madagascar and Nigeria. Unheated sapphires in royal blue color, in fine quality fetch the highest premium of all. Today many women wear sapphire because the calming nature of the blue colour associated with trust, loyalty and inner peace. They also range widely in colour from very pale blue to more intense royal blue, to very dark midnight blue. For this reason, they make a very versatile alternative engagement ring.

Blue sapphires that are eye-clean or entirely free of inclusions are uncommon, especially in larger sizes. However, blue sapphires with some internal inclusions are still highly valued, as long as the inclusions do not reduce brilliance, obscure color, or otherwise detract from the gemstone’s beauty. Blue sapphires of one-carat weight or more are not usually cut to calibrated sizes or standard shapes. Each gemstone is shaped to maximize the color and weight of the gemstone.

Heat treatment and diffusion make attractive blue sapphires out of common corundum that would have little or no value without treatment. Heat treatment is widely used in the international sapphire market, and it is estimated that well over 90 percent of all blue sapphire in the market today has been subject to heat treatment. Diffusion treatment is far more controversial, and diffusion-treated blue sapphires sell for much less than those which have only been heat-treated. Silk inclusions are also acceptable in blue sapphires, as long as they are not so dense as to compromise color or brilliance. In fact, the presence of silk inclusions shows that the sapphire is unheated, and this can increase the value of a sapphire.

In blue sapphires, cutting can influence color in surprising ways. Sapphires are dichroic gemstone, meaning their color varies depending on the angle from which it is viewed. Viewed in one direction, most blue sapphires appear blue to violet-blue. From another direction, they will appear slightly greenish blue. A skilled cutter will orient their gemstone so that the blue to violet-blue color shows through the finished gem’s crown.