When you’re thinking of blue gemstones, sapphire, September’s birthstone, is the one that is most likely to leap to mind first. And no wonder. Not only has it been used as a precious stone for thousands of years, but it is also second only to diamonds in hardness, which makes it extremely durable.
Sapphire is a form of the mineral corundum, which is made up of aluminum and oxygen atoms. In its pure form, corundum is clear—in fact, these white sapphires are often used as accent stones in jewelry. Trace amounts of iron and titanium give sapphires their classic hue, which can range from violet blue to greenish blue. Natural sapphires also come in other shades, such as yellow, purple, orange, and green, depending on the trace elements influencing their color.
With a nine on the Mohs scale of hardness, sapphire is suitable for any kind of jewelry, including rings that are worn daily. One of the most famous modern sapphire rings, which has a twelve-carat sapphire surrounded by diamonds, is Princess Diana’s engagement ring, given to her in 1981 by Prince Charles, which Prince William later used when he proposed to Kate Middleton. Sapphires are so tough that synthetic sapphires are used in many industrial applications, such as wristwatch crystals and shatter-resistant windows.
The name “sapphire” comes from the Latin word “sapphirus” and the Greek word “sappheiros,” which both mean “blue.” As you would expect of a stone with such a long history in diverse cultures, sapphire carries many folklore associations. It is believed to bring good fortune and protection from harm, and to promote wisdom and serenity.
The value of individual sapphires is judged on color, clarity, cut, and carats. Color is the most important factor: the purer the blue and the more intense the color, the more valuable the stone. It is not unusual for a sapphire to be heated to intensify its color; sapphires that are unheated, however, will generally be valued higher. The most valuable stones can be more expensive than diamonds on a per-carat basis.
Natural sapphires tend to have some inclusions, but fewer than rubies (another form of corundum). Some sapphires, known as “star sapphires,” exhibit asterism, where needle-like inclusions of rutile (titanium dioxide) throughout the stone reflect light to create the appearance of a luminous star. These are typically cut as cabochons to show off the effect. The cut of a sapphire, star or not, should be chosen to maximize the size of the stone while maintaining good proportions and showing off the best possible color.
Sapphires are found all around the world, in Asia, Africa, Australia, South America, and North America. While stones from Kashmir, Sri Lanka, are legendary for their pure blue color, high-quality sapphires can be found from any region.
Auction King regularly features sapphire bracelets, pendants, rings, earrings, and necklaces, including rare fancy sapphires in a range of colors. Their low opening bids and live-auction format give bidders the best opportunity to buy these high-value stones at prices well below retail. Sign up today for a free online account to find the sapphire piece you’ve been looking for!