No gemstone moves quite like an opal. Turn it in the light and flashes of blue, green, pink and red appear and disappear across its surface. The Victorians adored opals, and they remain one of the most romantic stones you can find in antique jewelry.

What makes an opal flash?

Opal is made of tiny spheres of silica packed together, with water held between them. In precious opal, these spheres are arranged in a neat, regular pattern. As light passes through, the spheres split it into the colors of the rainbow, much like light on a soap bubble. This is called play-of-color, and the size of the spheres decides which colors you see.

Types of opal

• White opal: a pale body color with soft flashes of color. The classic opal of Victorian and Edwardian jewelry.
• Black opal: a dark body color that makes the colors appear especially vivid. Found mainly at Lightning Ridge in Australia, and highly prized.
• Boulder opal: opal formed within ironstone, often cut with the brown host rock left on the back.
• Crystal opal: transparent to translucent, with color that seems to float within the stone.
• Fire opal: orange to red, often without play-of-color, and found mainly in Mexico.

Opals in history

The Romans treasured opals, believing they held the colors of every other gemstone. For much of the 19th century, opals suffered from a reputation for bad luck, often traced to an 1829 novel by Sir Walter Scott. Queen Victoria helped restore their popularity, wearing and giving opal jewelry, and the Victorians came to see opals as symbols of fidelity and assurance. The discovery of rich opal fields in Australia in the late 19th century then made them far more widely available, which is why they appear so often in late Victorian and Edwardian rings.

Opal is the birthstone for October and the traditional gift for a 14th wedding anniversary.

Caring for opals

Opals are softer and more delicate than most gemstones, so a little care goes a long way:

• Avoid sudden changes in temperature and keep them away from heat.
• Don't soak opals or use chemical cleaners. Wipe them with a soft, slightly damp cloth.
• Take opal jewelry off for washing, exercise and household tasks.
• Store them separately, so harder stones can't scratch them.

Browse our antique opal jewelry, or see our guide to cleaning antique jewelry safely.

Tiffany is the founder of Mayveda, a Fellow of the Gemmological Association of Great Britain (Gem-A) and a GIA-certified diamond grader.