Opal

Opal is a hydrated form of silica (SiO₂·nH₂O), containing 3 to 21 percent water within its structure. Unlike most gemstones that are crystalline, opal is amorphous — it has no crystal structure. Its famous play of colour is caused by the diffraction of light through microscopic spheres of silica arranged in a regular three-dimensional grid. When these spheres are uniform in size and spacing, they diffract white light into the spectral colours visible as the stone moves. Precious opal displays this play of colour; common opal does not.

Black opal, with a dark body colour that makes the play of colour more vivid, is the most valuable variety — fine specimens from Lightning Ridge can command prices exceeding diamond. White opal has a light body colour and is more affordable. Boulder opal forms on a host rock (ironstone) and is cut with the backing intact. Crystal opal is transparent or semi-transparent with vivid play of colour. Fire opal, found primarily in Mexico, has a warm orange to red body colour and may or may not show play of colour.

The ancient Romans considered opal the most precious gemstone because it contained all the colours of other stones. Pliny the Elder described it as having "the fire of the carbuncle, the brilliant purple of the amethyst, and the sea green of the emerald." In the Middle Ages, opal was believed to grant invisibility and was called "ophthalmios" (eye stone), thought to benefit eyesight. The discovery of vast opal deposits in Australia in the 1800s established the country as the world's opal capital.

Opal symbolises creativity, hope, inspiration, and innocence. It is believed to amplify emotions, release inhibitions, and encourage freedom of expression. In many traditions, opal is associated with spontaneity, imagination, and artistic vision. Its ever-changing play of colour is said to represent the full spectrum of human emotion and experience.

Opals require special care due to their water content and softness. Never use ultrasonic or steam cleaners. Clean gently with a damp, soft cloth. Avoid extreme temperature changes, prolonged direct sunlight, and very dry environments, which can cause opal to crack (called "crazing"). Store opal wrapped in a slightly damp cloth in a sealed container. Remove opal rings before any physical activity. Opal earrings and pendants are safer for regular wear than rings.

Australian black opal makes one of the most dramatic and unique centre stones for a special occasion ring, with no two stones ever alike. Opal pendants and earrings are excellent choices for regular wear since they are less exposed to impacts than rings. Opal doublets and triplets (opal slices backed with darker material) provide the play-of-colour effect at more accessible prices. For rings, choose a bezel setting that fully protects the stone.