On the nature of sapphires
Sapphire is one of the gem varieties of corundum. Actually all gem varieties of corundum are sapphires -- with the exception of those colored red, which are rubies. Thus, sapphires can come in many colors of the rainbow: blues, pinks, oranges, yellows, greens, purples as well as colorless and black. Of course, the first color we think of is blue.
The color in blue sapphires comes from iron and titanium. In violet sapphires, vanadium is responsible for the hue. Chrome produces a pink-shaded sapphire. Various amounts and mixtures of these elements result in other colors. For example, the consequence of a rather small amount of iron is a yellow or green sapphire while a mixture of iron and vanadium creates an orange stone.
On finding sapphires and what to look for
Sapphires are mined in many countries throughout the world. The most desirable specimens have come from Kashmir in India. Major mining in Kashmir has taken place since at least 1880 and the deposits have apparently been cleaned out. Other important deposits of sapphire are found in Australia, Burma (Myanmar), Sri Lanka, and Thailand.
Sapphires are evaluated according their color, clarity, cut, and carat weight. Each color of sapphire has its own quality variations. To prevent this article from becoming overly lengthy, we'll focus on the blue sapphires.
Color. The most sought after color when speaking of sapphires is an untainted shade of cornflower blue. The color should be medium to medium-dark with strong saturation that does not overly darken the stone or interfere with its brightness.
Clarity. Sapphires may have inclusions called rutile needles, which can have the desired outcome of a silky shine -- or when oriented in a certain pattern can result in the cat's eye or star effect. Other factors that can affect a sapphire's clarity include mineral crystals, partially healed breaks that look like fingerprints, color zoning, and color banding. Blue sapphires with outstanding clarity are unusual -- and quite precious.
Cut. Cut is extremely complicated when speaking of sapphires. Sapphire hardness on the Moh's scale is 9, the same as ruby. And like ruby, the hardness varies by direction and affects the lapidary's choice of cut. But lapidaries also must focus on factors like color zoning, pleochroism (color appears different from a different angle), and the lightness or darkness of a stone in order to maximize the color, proportions, and weight.
Carat. Blue sapphires can range in size from a few points to hundreds of carats. However most fine-quality sapphires are less than 5 carats. Larger fine-quality sapphires are rare but still they are more common than rubies of a comparable size and quality.
Historical notes and other interesting facts about sapphires
The color blue. Sapphire is Greek for blue and before 1800 the word was used to refer to various blue stones. In fact, from antiquity up til the Middle Ages when a person spoke of sapphire, he meant what we, today, call lapis lazuli.
Clear sapphires. Colorless sapphire is called leuko-sapphire. Leuko is Greek for white.
Lotus flower. The spectrum from reddish (not completely red though) to orange-yellow sapphire is called Padparadscha, an early German mispronunciation of the Sinhalese term padmaraga for lotus flower. Some think padparadscha sapphire colors should be called salmon or sunset. Others imaginatively compare the color to a ripe guava.
Green by day, blue by night. Not only do sapphires come in a rainbow of hues but they can also be more than one color at the same time: green at one end and blue on the other, yellow striped with pink like a piece of candy, and so on. Some sapphires can even change color in a way that seems more than magical, exhibiting the color of green during the day and violet-blue in the evening.
Prometheus's ring. According to Greek mythology, the world's first ring held a stone of sapphire. For innumerable years Prometheus was chained to a rock while an eagle pecked at his liver. He was guilty of stealing fire from the gods. Finally Zeus set him free but required him to wear a ring forged from the chains and the stone. The fragment of stone set in his ring is rumored to have been a sapphire, a stone that is the color of the very hottest part of a flame.
A Visigoth king. The oldest known European crown still intact and preserved for public display is the votive crown of the Visigoth King Reccesuinth made in the 7th century. The crown, not made to be worn but hung over an altar, is created from gold and encrusted with sapphires and pearls.
The Wedding Ring of England. The Coronation Ring, often called "the Wedding Ring of England, " was created for the Coronation of William IV in 1831 and continues to this day to part of the coronation ceremony. The ring features a large sapphire surrounded by diamonds. Two more diamonds decorate the shank and five rubies are set on the sapphire in the form of a cross. Altogether it weighs 84.45 carats.
Oldest stone in the Crown Jewels. The St. Edward's Sapphire is one of the oldest stones in Crown Jewels of the United Kingdom. According to legend King Edward the Confessor who began his reign in 1042 was accosted by a beggar on his way to Westminster Abbey. Having no money on hand to give the beggar, the king slipped the sapphire coronation ring off his finger and presented it instead. Years later, two of the kings envoys in Syria met a man who said he was St. John the Evangelist in an old inn. He told them he had received the ring from the king many years earlier in the guise of a beggar. He asked them to return the ring to the king with a message that he would see Edward very soon in heaven. Six months later the king died of chicken pox. His body was later disinterred and the ring recovered.
A symbol of heaven. Although today bishops tend to choose amethyst for their rings, since even before medieval times their stone of choice was the blue sapphire. The color is not only symbolic of heaven but sapphires were also thought to smooth over discordant situations and encourage pure thoughts.
21 jeweled bearings. In 1704 Nicolas Fatio de Duillier invented a way of making holes in rubies and sapphires so that metal workings of watches could fit inside. These were called jeweled bearings and greatly improved the accuracy of the then-popular pocket watches. The best watches were fitted with twenty-one jeweled bearings. Today, the process is still used but the jewels are usually synthetic.
Discovered in Montana by a womanizer. In 1894 sapphires were discovered by a hard-drinking womanizer by the name of Jake Hoover in Montana. A sapphire rush ensued that lasted until 1923 and yielded about 2.5 million carats of the best quality sapphires ever found in the United States.
Illegal to carry without a permit. Jammu and Kashmir is a state in northern India. Here it is law that you may not possess a sapphire without a license. Kashmir sapphires were thought to be the most beautiful sapphires in the world. The deposit south of the Zanskar valley was discovered around 1880 and the seams ran out within a short ten years. No other sapphires have even come close to their mysterious beauty.
53 carats. The Star of India, held by the American Museum of Natural History in New York, is quite possibly the largest cut star sapphire at 53 carats.
Presidential sapphires. The heads of Presidents Washington, Lincoln, and Eisenhower have been carved out three very large sapphires, each approximately 2000 carats.
Happy 45th! Not only is sapphire the birthstone of September but it is also the traditional gift for the 45th anniversary.
From the grocery store to the moon. Synthetic sapphire is used for the windows of supermarket scanners and spacecraft.
Resources and further reading
The Gemological Institute of America's Gem Encyclopedia.
Gemstones of the World. By Walter Schuman. Our go to book at Grimballs.
Jewels: A Secret History. By Victoria Finlay. An non-fiction adventure through time and place exploring the history of gems.
Smithsonian Institution National Museum of Natural History's Gem Gallery.
Wikipedia's article on St. Edward's Sapphire.