Sapphire

Sapphire and ruby are corundum. Except for the impurity elements that cause color, they are the same chemically, physically, and optically. When the word sapphire stands alone, it usually means the gem is blue. Sapphires also appear in colorless and black variations as well as a wide range of colors. They include violet, green, yellow, orange, pink, and purple. They’re considered fancy-color sapphires and designated by color, as in “yellow sapphire.” Clergy in the late Middle Ages favored blue sapphire for their ecclesiastical rings because its color symbolized heaven. Magicians said it led them to prophecies and allowed them to command spirits. People also turned to sapphire as medicine for eye ailments like cataracts. France’s fourteenth century King Charles V owned “an oval oriental sapphire for touching the eyes, set in a band of gold.” People took sapphire as an antidote for poison and poisonous bites. They believed the stone could clear the mind and skin and cure fevers, colds, and ulcers. They even enlisted it in their fight against the plague—at least those who could afford one did. The superstition and faulty science began to recede in the late eighteenth century. That’s when crystallographers determined that sapphire and ruby were the same species and moved toward categorizing them under the name corundum. For centuries, people used “oriental” to designate stones of a particular hardness that originated east of the Mediterranean. Eighteenth-century gem experts replaced that word with the new word “corundum” when describing sapphires. The word might not have been exact enough, but the idea was right. Corundum, no matter the color, was hard, and its primary source was in the East.

Sapphire Sources

 Of the more than two dozen places that produce sapphires, the most famous historical sources are the Kashmir region, which straddles Pakistan and India, as well as Myanmar and Sri Lanka. Kashmir, high in the Himalayas, is renowned for the finest of all sapphires. They are an intense, medium-dark blue, with a unique velvety appearance. The color is called “cornflower” because it resembles the almost fluorescent blue petals of that flower. Burmese sapphires are also beautiful. Their blue is intense, but somewhat darker than the blue of those from Sri Lanka.

Another long-time source of sapphires is Sri Lanka, formerly Ceylon. Connoisseurs put a premium on padparadschas, the pink-orange to pinkish orange sapphires from Sri Lanka. The blue sapphires from that country are called Ceylon. They are often lighter and brighter than stones from Myanmar. Today, the major sapphire sources are Madagascar, eastern Africa, Sri Lanka, and Australia. Madagascar is the most significant source of goodto fine-quality blue sapphire. Thai sapphires are usually dark blue in color, giving some stones an inky appearance. Cambodia supplies many finequality blue sapphires. Australia’s sapphires tend to be dark to very dark bluish green with strong pleochroism. Other sources include mines in Africa and the US, which are known for producing fancy-color sapphires.

Treated Sapphires

 The industry views heat treatment as not only common for sapphire, but also as practically an art form. This is because sapphire changes color when it’s “cooked” for the right amount of time and under the right conditions. Improved color is the main objective of heat-treating sapphires, while a secondary goal is improved clarity. Sapphires are also candidates for lattice diffusion treatment. Because the resulting color is sometimes only surface deep, it might disappear during polishing, be chipped away, or lost in other damage. Irradiation is another treatment that’s used on fancy-color sapphires, but the effect is temporary. Strong sunlight alone often destroys the resulting color

Sapphire Value Factors

 The most important influence on a blue sapphire’s value is its color, which can appear in a wide array of hues, tones, and degrees of saturation. Sapphire color ranges from very light to very dark violetish blue to greenish blue. The most highly valued sapphires are velvety, violetish blue to blue, in medium to medium-dark tones. Preferred sapphires also have strong to vivid saturation. The saturation should be as strong as possible without darkening the tone too much. Sapphires with these qualities command the highest prices per carat. At the other end of the price scale are commercial-grade sapphires with greenish blue bodycolor or strong greenish blue pleochroism, color zoning, a grayish look, and very light or very dark tone. Prices also vary for fancy sapphires. For example, the pricing on padparadschas can be as exotic as the color itself. Only the most experienced buyers can successfully make their way through a market where sapphires showing the slightest pink or orange might be offered as padparadschas. Generally, the color in the finest padparadschas is an intense pinkish orange hue. There are two phenomena typical to sapphire and both affect value. One is color change. Many color-change sapphires come from Sri Lanka and East Africa. Some in the trade compare them to fine alexandrites. Typically, with strong change, the actual colors are blue and purple. The other phenomenon is asterism. Star sapphires have traditionally been very popular, especially those with blue or black bodycolors. (The socalled black bodycolor is actually a very dark brown). The sharper and straighter its rays and the purer its blue—the less gray it shows—the more valuable a blue star sapphire. Black star sapphires are more fragile than other star sapphires. As you read in Assignment 6, they’re susceptible to parting, so they’re usually cut in a low cabochon for protection against being hit. Black star sapphires are relatively inexpensive. Local pride is also a factor in assessing value in the sapphire market. Buyers in the northern US place a premium on sapphires from the nearby mines of Yogo Gulch, Montana.