Opal

Opal Crystals

Opal is a hydrated amorphous silica (SiO₂·nH₂O) containing 3–21% water within its structure. Unlike most gemstones, opal is non-crystalline. Its famous play of color — the shifting rainbow flashes — is caused by diffraction of light through a regular array of silica spheres. When these spheres are uniform in size (150–400 nanometers), white light diffracts into spectral colors. Opal rates 5.5–6.5 on the Mohs scale.

The main varieties include white opal (light body color), black opal (dark body, most valuable, from Lightning Ridge, Australia), boulder opal (thin layer on ironstone), fire opal (transparent orange from Mexico), and pink and blue opal from Peru. Australia produces approximately 90% of the world's precious opal. Ethiopian hydrophane opal has become a significant source since 2008.

Our collection features pink opal, blue opal, and precious opal in various forms including raw specimens, polished pieces, towers, and bracelets. For other iridescent stones, see our labradorite and moonstone collections. Browse crystal jewelry for opal pendants. Free shipping on orders $150+.

Frequently Asked Questions

What causes opal's play of color?

Play of color is caused by light diffracting through a regular three-dimensional array of silica spheres within the opal. When these spheres are uniform in size and tightly packed, white light splits into spectral colors. The size of the spheres determines which colors appear — smaller spheres produce blues, larger ones produce reds.

What are the different types of opal?

White opal (light body with play of color), black opal (dark body, most valuable), boulder opal (thin layer on ironstone matrix), fire opal (transparent orange, may lack play of color), Ethiopian opal (hydrophane, absorbs water), and common opal (no play of color, found in pink, blue, and other colors).

How should I care for opal?

Opal contains water and can crack if it dries out too quickly. Store away from direct heat and prolonged sunlight. Do not use ultrasonic or steam cleaners. Clean with a soft damp cloth. Some collectors store valuable opals in sealed containers with a damp cotton ball in very dry climates.

Is Ethiopian opal different from Australian opal?

Yes. Ethiopian opal is hydrophane — it absorbs water and temporarily changes appearance when wet, returning to normal when dry. Australian opal is non-hydrophane and more stable. Ethiopian opal can be more prone to crazing in very dry environments. Both can show spectacular play of color.

Where does opal come from?

Australia produces about 90% of the world's precious opal. Lightning Ridge (NSW) is famous for black opal, Coober Pedy (SA) for white opal. Ethiopia's Wollo Province has been a significant source since 2008. Mexico produces fire opal. Peru produces pink and blue common opal.