Colors
- Rainbow play of color
- Described by body color: black or white
Browse other gems by color: White and colorless · Black · Blue · Green · Orange
Where Opal comes from
- Australia (about 95 percent of world supply since about 1850)
- Mexico
- Brazil
- Honduras
- Ethiopia
- Czech Republic
- Nevada and Idaho (US)
Opal meaning and history
The name: From the Greek "opallios", "to see a change in color".
The Roman scholar Pliny wrote about opal's shifting rainbow colors.
Its play of color was explained scientifically in the 1960s.
Meanings and powers attributed to gems are history and folklore. We report them; we do not claim a stone can do anything.
How hard is Opal?
Opal is 5 to 6.5 on the Mohs scale, where talc is 1, quartz 7 and diamond 10. Toughness, its resistance to chipping and breaking: very poor to fair. Wear with care to avoid scratching or breaking it.
See every birthstone on the hardness chart
How to clean and care for Opal
| Warm soapy water | The only safe method |
|---|---|
| Ultrasonic cleaner | Not safe (GIA: warm soapy water is the only safe way) |
| Steam cleaner | Not safe (GIA: warm soapy water is the only safe way) |
Heat, light and chemicals: Heat from intense light can cause crazing; high heat or sudden temperature change can crack it; attacked by hydrofluoric acid and caustic alkaline solutions.
Treatments to ask about
Can be impregnated with oil, wax or plastic, or given sugar or smoke treatments.
Can you wear Opal every day?
Delicate Soft or easily damaged. Best for pendants, earrings and occasional wear. Check other stones.
Compare Opal
Opal vs Tourmaline · Opal vs Moonstone
Frequently asked questions
What is Opal?
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.
What month is Opal the birthstone for?
October. It shares the month with Tourmaline.
How hard is Opal?
5 to 6.5 on the Mohs scale. Toughness: very poor to fair. Wear with care to avoid scratching or breaking it.
How do you clean Opal?
Warm soapy water: the only safe method. Ultrasonic cleaner: not safe (GIA: warm soapy water is the only safe way). Steam: not safe (GIA: warm soapy water is the only safe way).
What does Opal symbolize?
The Roman scholar Pliny wrote about opal's shifting rainbow colors. Its play of color was explained scientifically in the 1960s. These are traditions and history, not claims about what the stone can do.
Sources
- GIA: Opal care and cleaning (hardness, toughness, stability, cleaning, treatments)
- AGS: Opal (what it is, colors, sources, history)
- American Gem Society: Birthstones (birthstone months)
Checked October 16, 2026.