The Sapphire
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What Is the September Birthstone?

The September birthstone is sapphire, a variety of the mineral corundum. If you read our July ruby page, you already know this family: all corundum is sapphire except the red, which gets called ruby. That means sapphire comes in virtually every color. Blue, pink, yellow, green, orange, purple, teal, white. Even colorless. The only color it can't be, by definition, is red.

Blue sapphire is what most people picture when they hear the name, and it's the color that has defined the stone for millennia. The blue comes from trace amounts of iron and titanium within the crystal structure. More iron produces a darker, inkier blue. The ideal is a specific medium-dark shade with high saturation and a velvety quality that gemologists and dealers have spent centuries arguing about.

At 9 on the Mohs hardness scale, sapphire ties with ruby as the second-hardest natural gemstone after diamond. It has no cleavage, excellent toughness, and no sensitivity to light or chemicals. That combination makes it one of the most practical gemstones for daily wear. The name comes from the Greek sappheiros and the Latin sapphirus, both meaning simply "blue stone." In Sanskrit, it's sanipriya: sacred to Saturn.

September Birthstone Meaning & Symbolism

The Stone That Colored the Sky

The most evocative piece of sapphire mythology comes from ancient Persia. The Persians believed that the Earth rested on an enormous sapphire, and that the blue of the sky was nothing more than the stone's reflection cast upward. It's a gorgeous idea, and it tells you how deeply blue sapphire was embedded in the ancient imagination.

Greeks wore sapphire when consulting the oracle at Delphi, believing the stone sharpened their ability to interpret divine answers. Buddhists associated it with spiritual enlightenment. Hindu worshippers wore sapphire during prayer. And across medieval Europe, clergy wore sapphire rings to symbolize Heaven, while kings and queens wore it as protection against envy, harm, and poisoning. The stone's reputation for faithfulness made it the default gemstone for ecclesiastical and royal rings for the better part of a thousand years.

Royal Love and One Very Famous Ring

In 1981, Prince Charles proposed to Lady Diana Spencer with a 12-carat oval blue sapphire surrounded by fourteen diamonds. It was an unconventional choice for a royal engagement ring at the time, and it became one of the most photographed pieces of jewelry in history. When Prince William proposed to Kate Middleton in 2010, he used the same ring. Sapphire has been a symbol of royal love ever since.

The 5th, 45th, and 65th Anniversary Stone

Sapphire marks the 5th, 45th, and 65th wedding anniversaries. That makes it one of the most celebration-rich gemstones in the entire birthstone calendar. It is also, alongside diamond and ruby, one of the three gemstones most commonly chosen for engagement rings.

The History of the September Birthstone

Sri Lanka has been mining sapphires for over 2,000 years. Stones from the island traveled the Silk Road to reach ancient Rome and Greece, where they were set in rings, seals, and religious artifacts. But the sapphire that changed everything came from a landslide.

In 1881, a Himalayan landslide high in the mountains of Kashmir exposed a massive pocket of blue crystals. Between 1882 and 1887, miners extracted thousands of extraordinary stones. They were unlike anything the gem world had seen: a velvety, soft cornflower blue that seemed to glow from within, created by microscopic silk inclusions that scattered light in a way no other sapphire could replicate. Those five years of production created a legend. Kashmir sapphires remain the single most valuable colored gemstones per carat, regularly selling for $50,000 to over $200,000 per carat at auction. The mines have been virtually exhausted since the early 20th century.

The Star of India, a 563-carat star sapphire, sits in the American Museum of Natural History in New York. In 1964, it was stolen in a now-famous heist by Jack "Murph the Surf" Murphy and two accomplices, who climbed through an unlocked bathroom window. The gem was recovered months later in a locker at a Miami bus station. The Logan Sapphire (423 carats) and the Rockefeller Sapphire (62.02 carats, cornflower blue, originally purchased from an Indian maharaja in 1934) are also among the most celebrated sapphires in the world.

September Birthstone Color

Blue is sapphire's signature, but the stone's full range is enormous. "Fancy sapphires" include pink, yellow, orange, green, purple, teal, and the exceedingly rare padparadscha, a delicate pinkish-orange named after the Sinhalese word for "lotus blossom." Fine padparadscha sapphires from Sri Lanka sell for $10,000 to $30,000 per carat. Their color is so specific and so scarce that even experienced gemologists debate where the boundary lies between "padparadscha" and "fancy pink-orange."

In blue sapphires, the most valued shade is a pure, vivid medium-dark blue with strong saturation and even color distribution. The trade calls this "cornflower blue" when it has a soft, velvety quality, or "royal blue" when it's deeper and more saturated. Kashmir sapphires set the standard for cornflower; Myanmar (Mogok) stones define royal blue. Both command premiums that lesser origins struggle to match.

Most commercial sapphires are heat-treated to improve color and clarity. This is stable, permanent, and universally accepted. Untreated sapphires with natural top color fetch significantly higher prices. Star sapphires, which display a six-ray asterism (a star pattern that floats across the surface of cabochon-cut stones), occupy their own category entirely.