Velvety blue. Liquid blue. Evening-sky blue. Cornflower blue. Sapphire, beloved for centuries as the ultimate blue gemstone. The ancient Persian rulers believed that the earth rested on a giant sapphire and its reflection colored the heavens blue.

But like the endless colors that appear in the sky, sapphire is also found in many, many other shades besides blue, from the gold of a sunrise, to the fiery reddish-orange of sunset, to the delicate violet of twilight. Sapphire may even resemble the pale white gloaming of an overcast day. These diverse colors are referred to as “fancy” color sapphires.

A gift of a sapphire symbolizes a pledge of trust and loyalty. It is from this tradition that sapphire has long been a popular choice for engagement rings. One of nature’s most durable gemstones, sapphire shares this quality with its sister, the ruby. Sapphire is found in many parts of the world, but the most prized sapphires are from Myanmar (Burma), Kashmir and Sri Lanka. The purer the blue of the sapphire, the greater the price the gemstone can command, however, many people find that the darker hues of sapphire can be just as appealing.

Over the centuries, methods have been developed to enhance the purest hues of sapphire. This is now commonly achieved by controlled heating, a technique that not only improves color but also improves clarity. But heating will only improve the color if the gemstone already contains the chemistry required. Heating sapphires is a permanent enhancement, as lasting as the gemstones themselves.

With a hardness of 9 on the Moh’s scale, sapphire of any color is one of the hardest gemstones available save the diamond. Due to their crystal growth, larger sapphires are most often found in fancy brilliant cuts, like oval or cushion, large rounds and emerald cuts are markedly rarer to encounter.

Sapphire is the birthstone for September and the gem of the 5th and 45th anniversaries.