Gemstone Education: Sapphire: The Jewel of the Sky

Sapphire_blog_20140601 separates the sapphire facts from the fiction in this jewelry primer for September’s glittering birthstone.

Sapphire has been sought after for thousands of years as the ultimate blue gemstone. The ancient Persians believed that the earth rested on a giant sapphire that gave its blue reflection to the sky, hence the Latin name “sapphiru”, which means blue. The gem has long symbolized faith, remembrance, and enduring commitment.

According to tradition, God gave Moses the Ten Commandments on tablets of sapphire, making it the most sacred stone. This supposed “divine favor” is why sapphires often were the gem of choice for kings and high priests throughout history. In fact, the British Crown Jewels contain a number of notable sapphires. Prince Charles even gave Princess Diana a sapphire engagement ring.

Sapphire is the birthstone for September. It is also the recommended gem for couples celebrating their fifth and 45th wedding anniversaries. Both sapphire and its sister stone, ruby, are part of the corundum family, one of the strongest minerals on earth. The stone is mined in many parts of the world, including Australia, Cambodia, China, Kashmir, Kenya, Madagascar, Myanmar, Nigeria, Sri Lanka, Tanzania, Thailand, the United States and Vietnam. Sapphires from Kashmir and Myanmar are rarest and most prized because of their vivid blue, velvety look.

Although sapphire is virtually synonymous with blue, the stone also comes in a variety of fancy colors that includes colorless/white, pink, yellow, peach, orange, brown, violet, purple, green and many shades in between (except red, because a red sapphire would be called a ruby). Some sapphires that are cut into a cabochon (dome) shape even display a six-rayed white star. These are called star sapphires, and the ancients regarded them as powerful talismans that protected travelers.

Like other gemstones, color is the main determining factor when judging the value of a sapphire. As a rule, the most valuable sapphires have a medium intense, pure vivid blue color and hold the brightness of their color under any type of lighting. Any color undertones – usually black, gray or green – will reduce a stone’s value. Although a pastel stone would be less valued than a deeper blue one, it would be more valuable than a stone considered too dark.

In selecting your sapphire, keep in mind that the finest stones are “eye clean”, with little or no inclusions (flaws) visible to the naked eye. Sapphire is readily available in sizes of up to 2 carats, but gems of 5-10 carats are not unusual. The stone is most often cut in a cushion shape – a rounded rectangle – or an oval. But smaller stones are available in round brilliant cuts and a variety of fancy shapes, such as triangle, square, emerald, marquise, pear, baguette, cabochon and others.

Some of the more noted sapphires include the Logan Sapphire, a 423-carat cushion-cut stone from Sri Lanka currently in the Smithsonian Institution in Washington, D.C., and a 258-carat stone set in the Russian crown and kept in the Diamond Fund in Moscow. With a hardness of 9 on the Mohs scale, sapphire is harder than any other gemstone except a diamond. This quality makes it extremely durable for everyday jewelry pieces subject to repeated impact, such as rings and bracelets.

In general, sapphire can be cleaned with soapy water or commercial solvent and a brush. It is estimated that about 90% of sapphires on the market today have been heated to maximize their color and clarity. This process is permanent and completely stable. Perfect natural, untreated gems are exceptionally rare and very expensive.

Some colorless or pale stones are treated with chemicals (diffusion treated), which improves the surface color only. This could create a problem if the stone is ever chipped or nicked and needs to be recut or repolished. In addition, some fancy colored sapphire is irradiated to give it a more intense shade. These effects are temporary and can fade in light or heat.

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