Sapphire is the traditional birthstone for the month of September, is the mystical birthstone for the month of May, and the ayurvedic birthstone for the month of August.
Most commonly refers to a blue gem variety of Corundum, but other colored varieties of Corundum are also described as sapphire, except red Corundum, which is better known as Ruby.
It was not until the 18th century that it was clearly established that sapphires and rubies are, in fact, the same mineral--corundum, natural aluminum oxide. The name corundum is probably derived from the Sanskrit word kuruvinda meaning "ruby", the name given to the red variety of corundum. In ancient literature, the term "sapphire" appears to have mostly referred to lapis lazuli, although blue corundum has itself been prized since at least 800 BC. Sapphires name derives from the Greek word sappheiros, "blue stone" (the gem meant apparently was not the one that now has the name, but perhaps rather "lapis lazuli," the modern sapphire being perhaps signified by Greek hyakinthos which was derived from the name of the hyacinth flower).
When it is found in other colors (any other but red) it is called "sapphire". Although popularly thought of as being blue, sapphire also occurs as colorless, green, pink, and a wide range of other hues. Rare pink-orange stones are called padparadscha meaning “lotus flower” in Sinhalese, and sapphire that appears blue in daylight and reddish or violet in artificial light is called alexandrine or alexandrite sapphire. Sapphires are commonly pleochroic--that is, they appear to be differently colored when viewed from different directions. When blue, sapphire is colored by trace titanium and iron, when pale green, yellow, or brown it is colored by iron. From medieval times until the end of the 19th century, green sapphire was referred to as "Oriental peridot" and yellow sapphire as "Oriental topaz". When sapphire is pink it is caused by very small traces of chromium. With increasing amounts of chromium, pink sapphire forms a continuous color range with ruby. Vanadium, nickel, and cobalt can also alter colors.
Transparent sapphire is most commonly faceted, while star sapphire and other nontransparent varieties are cut as cabochons. Some sapphire is even carved or engraved despite its hardness. Next to diamond, corundum is the hardest mineral on Earth. It crystallizes in the hexagonal system, forming dipyramidal or rounded barrel-shapes.
Non-gemstone corundum is used as an abrasive for grinding optical glass and for polishing metals and has been made into sandpapers and grinding wheels. When naturally mixed with magnetite it forms emery. It is also used in high-temperature ceramics because of its high melting point.
Corundum is most abundant in metamorphic rocks, and in silica-deficient igneous rocks such as nephrite syenites. Large deposits are rare, however. Most sapphires and rubies are mined from alluvial deposits, where their higher density concentrates them when weathered from their original source. Myanmar, Sri Lanka, Nigeria, and Thailand are famous gemstone sources, but there are also deposits in Australia, Brazil, Kashmir, Cambodia, Kenya, Malawi, Colombia, and the US.
Traditionally, sapphire symbolizes nobility, truth, sincerity, and faithfulness. It has decorated the robes of royalty and clergy members for centuries. Its extraordinary color is the standard against which other blue gems—from topaz to tanzanite—are measured.
For centuries, sapphire has been associated with royalty and romance. One of the oldest sapphires is St. Edward's sapphire, set in the finial cross of the British Imperial State Crown, and believed to date from Edward the Confessor's coronet in AD 1042. Blue sapphire was widely used in the jewelry of the medieval kings of Europe and was considered the stone most fitting for ecclesiastical rings. The association was reinforced in 1981, when Britain’s Prince Charles gave a blue sapphire engagement ring to Lady Diana Spencer. Until her death in 1997, Princess Di, as she was known, charmed and captivated the world. Her sapphire ring helped link modern events with history and fairy tales. In ancient Greece and Rome, kings and queens were convinced that blue sapphires protected their owners from envy and harm.
In ancient Greece, and later in the Middle Ages, there was belief that sapphires cured eye diseases. During the Middle Ages, the clergy wore blue sapphires to symbolize Heaven, and ordinary folks thought the gem attracted heavenly blessings and set prisoners free. Medievel alchemists related it to the element air, and sapphires were also believed to be an antidote against poisons and endowed with a power to influence spirits at that time. In other times and places, people instilled sapphires with the power to guard chastity, make peace between enemies, and reveal the secrets of oracles. In the East, the sapphire is regarded as a powerful charm against the evil eye.
In folklore, history, art, and consumer awareness, sapphire has always been associated with the color blue. Most jewelry customers think all sapphires are blue, and when gem and jewelry professionals use the word “sapphire” alone, they normally mean “blue sapphire.”