Opal: meaning, symbolic properties, care and fragility

What is opal?

Opal is not quite a mineral like the others: it is made of hydrated silica, that is to say the silica of quartz containing water, but organised without crystals. Geologists speak of a mineraloid. Water generally makes up 3 to 9% of its mass, sometimes more.

The famous play of colour of precious opal comes from its structure: tiny spheres of silica, stacked very regularly, diffract light. When the stacking is disordered, the stone does not show this play: this is common opal, often plain, milky or coloured (pink, blue, green). A third family is fire opal, yellow-orange to red, transparent, with or without play of colour.

It forms when water carrying silica circulates through cracks in rock and deposits it there, often after dry periods that lower the level of the groundwater. Australia supplies most of the world's precious opal, notably Coober Pedy (light opal) and Lightning Ridge (black opal). It is also found in Ethiopia, Mexico (fire opal), Slovakia, Hungary and elsewhere.

The word comes from the Sanskrit upala (“precious stone”), through the Greek opallion and then the Latin opalus. The deposits of central Europe were known as early as Roman times; those of Australia were not mined until the second half of the 19th century.

Traditional symbolism

Because it seems to contain every colour, opal has been linked to imagination, creativity and memory. For the Romans it was of immense value, and its name was for a long time associated with hope and good fortune.

The reputation as an unlucky stone is later: it is often traced to a novel by Walter Scott (1829), although the superstition may have existed before it. In modern tradition the stone belongs above all to October. It is associated with emotion, sensitivity and inspiration, with this nuance: these images are symbolic, never proven.

Traditional correspondences

How to use it

• As evening jewellery: rings, pendants and earrings for gentle use, removed for activities that rub or knock.
• As a cabochon or small collector's object: the stone is looked at more than handled. Move it in front of a lamp: the play of colour changes with the angle.
• In visual meditation: placing the stone in front of you and following its reflections with your eyes is a simple exercise in attention, with no promises attached.
• As an October gift: a classic birthday present.

For more affordable coloured opals, see pink opal and blue opal, which are common opals. For another milky sheen, moonstone is a less fragile alternative.

Care and cleansing

Opal is soft for a gemstone (5.5 to 6.5) and contains water: it calls for gentleness.

• Cleaning: a soft cloth, slightly damp, or lukewarm water very briefly, then drying. No ultrasonic cleaners, no steam, no household products.
• Heat and dryness: an opal that dries out can crack into fine crazing. Avoid radiators, a window in the sun and drying cabinets. Some collectors store precious pieces wrapped in a cloth that is barely damp.
• Knocks: store it separately, wrapped in cloth, so that harder stones do not scratch it.
• Salt and prolonged soaking: to be avoided.

For symbolic cleansing, moonlight, gentle smoke or a moment of calm are enough. See our guide.

Recognising real opal

• Doublets and triplets: a thin layer of opal glued onto a dark backing (sometimes onyx or glass), sometimes topped with a dome of crystal or glass. They are legitimate if they are declared; seen from the side, the line of the glue can be made out.
• Synthetic opal: made in a laboratory (Gilson is a well-known name). Its colour patterns often look regular, like “lizard skin”.
• Glass imitations: most “opalites” sold as jewellery are milky glass, unrelated to opal. Neither deep play of colour nor structure: a uniform bluish tint is a warning sign.
• Dyed opals: common opals can be coloured; a very bright, uniform colour should be disclosed.

Our supplier's file does not always describe these cases: always ask for the exact nature (natural, doublet, glass) before buying.

How to choose

For a first purchase, favour a whole common opal (cabochon, bead, small sphere): it is affordable, and its fragility matters less than with a precious piece. A quality precious opal is judged by its play of colour (vivid, visible from several angles), the absence of cracks and the thickness of the layer. Its price rises very quickly with these criteria.

Avoid unusually cheap pieces sold as “black Australian opal” without further detail: they are often doublets, glass or dyed material. For the vocabulary, see the glossary and our guide to gemstone jewellery.

Frequently asked questions

Also read

The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to Guide to stones.