September Birthstone: Sapphire
The September birthstone is sapphire. Sapphire is corundum, the same mineral as ruby. Blue is the classic color, but it also comes in violet, green, yellow, orange, pink and purple. Below: where it is mined, how to choose it, treatments to ask about, its history and how to clean it.
Sapphire facts
| Color | Blue, also other colors |
|---|---|
| Mineral | Corundum (ruby is the red variety) |
| Hardness | 9 on the Mohs scale (diamond is 10) |
| Main sources | Sri Lanka, Myanmar, Madagascar, Australia, Thailand, United States (Montana) |
| Anniversary gem | 5th and 45th wedding anniversary |
Choosing sapphire
- The best sapphires have strong to vivid color. Kashmir sapphires, intense and velvety, set the standard for blue.
- Sapphire also comes in violet, green, yellow, orange, pink and purple. Padparadscha, a pinkish orange sapphire, is rare and valuable.
Sapphire treatments
- Heat treatment is common and its results are permanent, so the trade accepts it.
- Lattice diffusion, fracture filling and dyeing are less common and need special care. Diffusion color can sit so close to the surface that it is lost if the stone chips or is recut, and filled or dyed sapphires can be damaged by mild acids such as lemon juice.
- Before you buy, ask whether the sapphire is treated and by what method.
Is sapphire good for everyday wear?
Sapphire is 9 on the Mohs scale, with excellent toughness and no cleavage (a tendency to split when struck). GIA says that makes it a great choice for rings worn every day.
Sapphire history
- People in ancient Greece and Rome believed blue sapphire protected its owner from harm and envy.
- Sapphires were found in Kashmir around 1881, when a landslide in the Himalayas uncovered cornflower-blue crystals.
How to clean sapphire
- Warm, soapy water and a soft brush: always safe.
- Ultrasonic cleaner: usually safe for untreated and heat-treated stones.
- Steam cleaner: usually safe for untreated and heat-treated stones.
Fracture-filled or dyed sapphires should only be wiped with a damp cloth.
September birthstone and birth flower
September also has two birth flowers: the aster and morning glory, which stand for patience, love and affection. The Birth Flower Finder covers every month.
Buying for someone not born in September? The Birthstone Finder shows every month's stones and colors in one chart. Sapphire is also given for wedding anniversaries; the Anniversary Calculator shows which one is coming up next. If the gift is a surprise, a birthday countdown counts down to the day.
Birthstones for other months
September Birthstone questions
What is the September birthstone?
Sapphire. It is the only birthstone for September on the modern US list.
What color is the September birthstone?
Sapphire: blue, also other colors. The best sapphires have strong to vivid color. Kashmir sapphires, intense and velvety, set the standard for blue.
Are sapphire and ruby the same stone?
They are the same mineral, corundum. Red corundum is ruby, the July birthstone; sapphire is classically blue but also comes in violet, green, yellow, orange, pink and purple, including the rare pinkish orange padparadscha. Both are 9 on the Mohs scale, second only to diamond.
Is sapphire an anniversary gem?
Yes. GIA gives sapphire for the 5th and 45th wedding anniversaries.
Published October 7, 2026. Last updated October 7, 2026.