Onyx: meaning, symbolic properties, care and fake onyx

What is onyx?

Onyx is a variety of agate, which is itself a variety of chalcedony, that is to say quartz formed from microscopic crystals. Its composition is that of quartz: silica, SiO2. What sets it apart from classic agate is the shape of its bands: they are straight and parallel, alternating a dark and a light colour, whereas agate's bands form curves and circles.

The name comes from the Greek onyx, meaning “fingernail” or “claw”. According to a very widespread explanation, the stone resembles a fingernail tinted pink; the exact origin of this image is told in several different ways. In antiquity it was widely used for cameos and intaglios: the white layer was carved so that it stood out against the dark background, the ideal use for a layered stone. Sardonyx, a close relative, alternates reddish-brown and white bands.

There are varieties with special names: nicolo (dark blue and white bands) or “eye” onyx (rings around a dark spot). In today's trade, what is simply called “onyx” is most often a stone of deep black, sometimes with a white edge, cut into beads, cabochons or spheres.

Traditional symbolism

Its dark colour has always inspired images of restraint, sobriety and quiet strength. In the lapidary tradition it is linked to self-mastery, discipline and perseverance. Some authors connect it with keeping a distance from outside noise, others with “closing” one period in order to begin a new one.

These readings are symbolic traditions, not proven effects. They have varied greatly over the centuries: for the Romans, onyx was mainly a material for carving; in the Middle Ages, lapidary texts loaded it with darker images, before modern jewellery made it an elegant, neutral stone. Choose it first and foremost because you like it.

Traditional correspondences

The following correspondences are common in contemporary esoteric literature; they are not unanimous.

How to use it

• As jewellery: beads, bracelets, pendants or rings. Its plain colour goes with everything, which makes it a wardrobe stone as much as a symbol.
• Displayed: a black sphere or egg on a desk or shelf makes a restrained decorative object, often chosen as a point of reference for refocusing.
• In meditation: held in the hand for a few minutes, a smooth, cool stone serves as a point of attention. The gesture matters, not the stone.
• As a gift: onyx suits a first piece of stone jewellery, for a man as well as for a woman.

To pair it with stones, consider neighbouring blacks such as black obsidian or black tourmaline, or the warm glow of tiger's eye.

Care and cleansing

With a hardness of about 6.5 to 7, onyx resists the scratches of everyday life and can be cleaned in lukewarm water with a little mild soap, then dried with a cloth. A few precautions:

• Avoid acids (vinegar, descaling products), especially if the piece is in fact calcite (see below).
• Avoid intense heat and prolonged sunlight: the black colour comes from a dye lodged in the stone; it is stable in normal use, but it is better not to expose it to extremes.
• No salt and no prolonged soaking for pieces that are glued or mounted (beads strung on thread, set jewellery).
• Smoke from sage or incense, a while on a bed of selenite, or moonlight are gestures of symbolic purification that pose no risk to the stone. See our guide to cleansing and recharging your stones.

Recognising real onyx and avoiding surprises

Three situations occur, and nobody is at fault if the seller says so:

• Dyed black onyx. Natural black bands are rare; the old practice, which goes back to antiquity, is to dye a pale chalcedony. A stone of perfectly uniform black is therefore very probably coloured. This treatment is long-established and accepted, but it should be disclosed.
• “Marble onyx” or “Algerian onyx”. This trade name refers to a travertine or banded calcite (sometimes called alabaster), with a hardness of 1.5 to 3, showing green, brown or white bands. It is a very pretty stone for objects (lamps, trays), but it is not onyx in the mineralogical sense. A knife scratches it easily, and it reacts to vinegar.
• Black glass and plastic. A bead that is too light, warm to the touch or too perfect should be treated with suspicion. Real stone feels cool and heavy for its size.

A further case exists in opal work: a glued assembly of opal on an onyx base is sometimes called “black opal” (a doublet). See our page on opal.

How to choose

For jewellery, prefer a stone polished without chips, whose beads have clean, regular drill holes. For a sphere or an egg, look at the surface under a lamp: small holes or deep cracks are normal in travertine, but not in chalcedony. A piece sold with its white bands visible is generally the least treated.

As for budget, onyx is an affordable stone: a very high price for a simple black bead is no sign of quality. To learn more about the vocabulary (natural, treated, reconstituted), see our guide to choosing and caring for your stones and the stone glossary.

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.