How Opal and Tourmaline differ in what they are, color, hardness and care.
| Opal | Tourmaline | |
|---|---|---|
| What it is | A gem whose play of color comes from tiny silica spheres that diffract light. Opals with this effect are called precious opals. Opal holds 3 to 21 percent water. | A family of related minerals that comes in more colors than almost any other gem. It can become electrically charged when heated or squeezed. |
| Birthstone for | October | October |
| Colors | Rainbow play of color; Described by body color: black or white | Pink; Red (rubellite); Green (verdelite, chrome tourmaline); Blue (indicolite); Neon blue to green (Paraiba, colored by copper); Brown to yellow (dravite); Black (schorl); Colorless (achroite); Watermelon (green and pink) |
| Mohs hardness | 5 to 6.5 | 7 to 7.5 |
| Toughness | Very poor to fair. Wear with care to avoid scratching or breaking it. | Fair. |
| Everyday wear | Delicate | Wear with care |
| Ultrasonic cleaner | Not safe (GIA: warm soapy water is the only safe way) | Not recommended |
| Main sources | Australia (about 95 percent of world supply since about 1850), Mexico, Brazil, Honduras | Brazil, Sri Lanka, Nigeria, Mozambique |
| Common treatments | Can be impregnated with oil, wax or plastic, or given sugar or smoke treatments. | Often heated or irradiated; heat treatment is stable. |
Tourmaline is the harder of the two (7 to 7.5 on the Mohs scale). Both are October birthstones, so either makes a fitting gift. Choose by the color you love and how the piece will be worn; for a ring worn every day, the tougher stone will last better.
Sources: GIA: Opal care and cleaning, AGS: Opal, GIA: Tourmaline care and cleaning, AGS: Tourmaline. Checked October 16, 2026.
Birthstone of the month
On the first of each month: that month's birthstone, what it means and how to care for it.
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