October Birthstones: Opal and Tourmaline
October has two official birthstones: opal and tourmaline. Every one counts, so you can choose by color, hardness or taste. Each is described below.
Opal, an October birthstone
| Color | Flashes of many colors |
|---|---|
| Mineral | Hydrated silica |
| Hardness | 5 to 6.5 on the Mohs scale (diamond is 10) |
| Main sources | Australia, Ethiopia, Mexico, Brazil, United States |
| Anniversary gem | 14th wedding anniversary |
Choosing opal
- Its flashes of rainbow color, called play-of-color, come from light bending around tiny spheres of silica.
- Play-of-color, its brightness and its pattern decide the value, and no two opals look alike.
Opal treatments
- Opal may be treated by soaking it in oil, wax or plastic.
- Doublets and triplets are thin slices of opal glued to a backing; a triplet also has a clear quartz dome on top. Long soaking in water can weaken the glue, so ask which kind you are buying.
Opal history
- Bedouins believed opal held lightning and fell from the sky in thunderstorms.
- Australia is the most productive source; Lightning Ridge is known for black opal.
How to clean opal
- Warm, soapy water and a soft brush: always safe.
Clean with warm, soapy water, but do not soak it, keep it from high heat, and store it apart from harder gems.
Tourmaline, an October birthstone
| Color | Many colors, including pink and green |
|---|---|
| Mineral | Tourmaline (a group of related minerals) |
| Hardness | 7 to 7.5 on the Mohs scale (diamond is 10) |
| Main sources | Brazil, Afghanistan, Pakistan, Kenya, Madagascar, Mozambique, United States (California, Maine) |
| Anniversary gem | 8th wedding anniversary |
Is tourmaline good for everyday wear?
At 7 to 7.5 on the Mohs scale, GIA says tourmaline is generally suitable for everyday wear. It stands up to light and most chemicals, but heat can damage it.
Tourmaline history
- The "Caesar's Ruby" pendant in the Russian crown jewels is red tourmaline.
- A Spanish conquistador who found green tourmaline in Brazil in the 1500s took it for emerald.
How to clean tourmaline
- Warm, soapy water and a soft brush: always safe.
- Ultrasonic cleaner: not recommended.
- Steam cleaner: not recommended.
Heat can damage it. Warm, soapy water and a soft brush are best.
October birthstone and birth flower
October also has two birth flowers: the marigold and cosmos, which stand for creativity, passion and joy. The Birth Flower Finder covers every month.
Buying for someone not born in October? The Birthstone Finder shows every month's stones and colors in one chart. Opal and tourmaline are 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
October Birthstones questions
What is the October birthstone?
October has two birthstones: Opal and Tourmaline. All of them are official, so you can choose the one you like best.
What color is the October birthstone?
Opal: flashes of many colors. Its flashes of rainbow color, called play-of-color, come from light bending around tiny spheres of silica. Play-of-color, its brightness and its pattern decide the value, and no two opals look alike. Tourmaline: many colors, including pink and green.
Which October birthstone is the hardest?
Tourmaline, at 7 to 7.5 on the Mohs scale. Opal is 5 to 6.5.
Is opal a birthstone?
Yes, one of October's two. Opal is hydrated silica, known for its play-of-color. At 5 to 6.5 on the Mohs scale it is one of the softest birthstones: only pearl and turquoise can be as soft or softer. No two opals look alike.
Is opal an anniversary gem?
Yes. GIA gives opal for the 14th wedding anniversary.
Why does October have more than one birthstone?
The US list from 1912 has been updated a few times. Pink tourmaline was added to October in 1952.
Published October 7, 2026. Last updated October 7, 2026.