The September birthstone is sapphire, a variety of the mineral corundum. It is famous for its blue, but it occurs in almost every color except red, which is ruby. Rating 9 on the Mohs scale, it is one of the most durable gems for daily wear. By tradition sapphire stands for sincerity, truth and faithfulness.
What is the birthstone for September?
Sapphire is September's only birthstone on the American list used by Jewelers of America and the American Gem Society. It was already there in 1912, when the list was first standardized, and no revision has touched it.
The British National Association of Jewellers specifies blue sapphire and gives lapis lazuli as the alternative. Lapis is an opaque deep-blue rock, often flecked with gold-colored pyrite, and a much less costly way to wear September's color.
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What does sapphire mean?
The Gemological Institute of America sums up sapphire's traditional symbolism as sincerity, truth, faithfulness and nobility. For centuries it was the stone of kings and clergy.
- Protection. The elite of ancient Greece and Rome believed blue sapphires protected their owners from harm and envy.
- Heaven. Medieval clerics wore sapphires because the blue symbolized Heaven. The ancient Persians believed the earth rested on a giant sapphire, which made the sky blue.
- Fidelity. The link with faithfulness helps explain sapphire engagement rings. The best known is the roughly 12-carat blue sapphire worn by Princess Diana and later given to Kate Middleton.
In the Middle Ages sapphire was also thought to cure plague boils and diseases of the eye and to work as an antidote to poison. It does none of those things. Such claims belong to the history of medicine, not to its practice.
What color is the September birthstone?
Blue, by long tradition. Pure corundum is colorless; a few hundredths of a percent of iron and titanium turn it blue, and the more iron, the darker the stone.
Other trace elements give other colors, sold as "fancy" sapphires:
- Pink, yellow, orange, green, violet and purple sapphires, plus shades in between.
- Padparadscha, a rare pinkish orange named after the lotus flower.
- Color-change sapphires, which usually go from blue in daylight to purple under a lamp.
- Star sapphires, cut as domes, in which tiny needle-like inclusions reflect a six-rayed star.
So a September birthday is not tied to blue. A pink or yellow sapphire is every bit as much a birthstone.
How sapphires are treated
Sapphires are often treated to improve their color or clarity.
- Heat treatment is common. Its results are permanent, and the trade accepts it. Milky white "geuda" sapphires from Sri Lanka, for instance, can be heated to a rich blue.
- Lattice diffusion adds color that can be so shallow that chipping or recutting the stone removes it.
- Fracture filling and dyeing are less stable. Even a mild acid such as lemon juice can damage these stones.
Before buying, ask whether the sapphire has been treated and by what method.
Where sapphires come from
Three historic sources set the standard for blue. Kashmir sapphires were discovered around 1881, when a landslide high in the Himalayas exposed crystals of "cornflower" blue; production since has been sporadic, and the stones are legendary. Myanmar, formerly Burma, yields rich, intense blues from the Mogok area. Sri Lanka has produced sapphires for more than 2,000 years.
Sapphires are also mined in Thailand, Cambodia, Australia, Madagascar and the United States, in Montana. Thailand is a major center for cutting and treating stones as well.
How to care for sapphire jewelry
Sapphire has excellent toughness and no cleavage, the tendency of some gems to split along a plane. It handles everyday wear in a ring better than nearly any colored stone.
- Warm, soapy water is always a safe way to clean it.
- Ultrasonic and steam cleaners are usually safe for untreated, heat-treated and lattice diffusion-treated sapphires.
- Fracture-filled or dyed stones should be cleaned only with a damp cloth.
- Keep sapphires in their own pouch. They scratch most other gems, and a diamond will scratch them.
Sapphire gift ideas for a September birthday
- A blue sapphire ring is the classic choice and stands up to daily wear.
- Studs or a pendant in a small, well-colored stone keep the cost down.
- A fancy color. Pink or yellow sapphire suits someone who rarely wears blue.
- A star sapphire makes a distinctive ring, with strong vintage character.
- Lapis lazuli beads or cufflinks give the deep blue of September at a modest price.
- At the top end, price depends on color, size, origin and whether the stone is unheated; buy with a laboratory report.
Sapphire is also the gem of the 5th and 45th wedding anniversaries, as our guide to gifts for every wedding anniversary shows.
September birth flowers: aster and morning glory
September's birth flowers are the aster and the morning glory. The aster, a daisy-like flower of early autumn in purple, pink and white, stands in the traditional language of flowers for wisdom, patience and love. The morning glory, a climber whose trumpets open at dawn and fade by afternoon, stands for affection. Purple asters look good next to a blue sapphire. Treat the meanings as a charming custom; nobody checks. All twelve months are covered in our guide to birth flowers by month.
A month either way: August has peridot, spinel and sardonyx, and October has opal and tourmaline. The year at a glance is in birthstones by month.