Onyx

The onyx we work in the workshop is a banded calcareous stone: it forms as calcium-rich water deposits layer upon layer in caves, springs and cavities in the rock. It is made of the same calcite crystals as marble, but arranged in dense, parallel bands that light can pass through. This is why it is the natural stone best suited to being backlit: place a light source behind a slab and the wall becomes a lantern. It should not be confused with the jeweller's onyx, an opaque chalcedony, black or banded in black and white: in the home, onyx always means this translucent stone.

The blocks come mainly from the Middle East, Turkey, Pakistan and Mexico, with a few European quarries. In our marble catalogue you will find Honey Onyx and Amber Onyx; among the natural stones, onyxes crossed by golden veins.

• Colour. From milk white to honey, from amber to green, through to pink and red: each tone is set by the minerals the water carried with it as the stone formed.
• Veining. Undulating bands, like clouds or currents; against the light the pattern changes completely from what you see with the lamp off. Consecutive slabs from the same block lend themselves to book-matching.
• Hardness. It is as soft as marble and can be scratched by a steel blade, but it is also more brittle: the bands are planes of weakness and natural fractures are common. That is why slabs arrive at the workshop already consolidated with resin, with a mesh bonded to the back, and are worked that way.
• Acids. Like marble it is calcium carbonate, and it is even more vulnerable to acids: lemon, vinegar, wine and limescale removers dull it permanently.

Onyx gives its best where it is looked at rather than worked on. In the kitchen it is the stone of the backlit island: a book-matched onyx base lets the light through and the room lights up, while the actual worktop can stay in a sturdier marble, in quartz or in Dekton. As a splashback, breakfast bar or upstand it is a statement choice. As an everyday worktop, with acids and pans, we do not recommend it.

In the bathroom it is at home: book-matched walls, showers that turn into stone lanterns, vanity tops, washbasins and baths carved from the solid, such as the Mida basin among our furnishing elements. Water does it no harm; acids do.

On floors and staircases it calls for judgement: only in rooms with little foot traffic, honed, and never on well-trodden steps, because it is soft and scratches. In three-dimensional walls it lends itself to inlays and backlit blocks. For outdoors the answer is no: sun, frost and acid rain degrade it within a few seasons.

Then there is light itself. In the Sculptures atelier (pages in Italian) onyx becomes a lamp: the Brace table lamp in honey onyx (EUR 1,250), the Alba floor lamp in white onyx (EUR 4,000) and the Plenilunio pendant (EUR 3,650), with panels brought down to a few millimetres so that the stone glows like parchment.

• Polished. The natural finish for onyx: it brings the slab to a mirror, heightens the depth of the bands and the translucency. It is what we recommend for walls, counters and every backlit surface.
• Honed. Smooth but matt; it softens reflections, hides fine scratches better and remains the only sensible choice for a floor or a vanity top in frequent use.
• Brushed, sandblasted, bush-hammered. Not advised: the stone is too soft and the bands flake under brushes and points. All the terms are explained on our finishes page.

Slabs are worked in 2 or 3 centimetres, like marble worktops. For backlighting, thickness matters: at 2 centimetres the light passes well and the pattern stays legible; at 3 the tone deepens but the light source must be stronger. The light is designed together with the stone: warm-white LED panels spread behind the whole slab to avoid the shadows of spot sources, with cables and housings planned in the 3D model before cutting.

• Book-matching. Two consecutive slabs opened like the pages of a book, the veining mirrored along the joint: the most theatrical gesture on a bathroom wall or the side of an island.
• Mitred waterfall. The top runs down the side with a 45-degree joint and the band carries on unbroken, as if the block were solid.
• Edges. On onyx the edge is worked as a light bevel or a polished square edge; no deep moulded profiles, which would weaken the slab.

The habits are those of marble, with a little more attention. Warm water, pH-neutral soap and a soft cloth; wipe up spills at once; never limescale remover, lemon, vinegar, alcohol or abrasive powders. The impregnating sealer applied in the workshop slows absorption and is renewed when the drop test calls for it, usually once a year. Backlit surfaces are best checked with the light off, under the room's own light: that is where marks and fingerprints show. An acid mark or a scratch can be removed by re-polishing: the stone comes back as new. Everything else is in our guide to caring for a marble worktop.

If you are after the piece that is looked at, the comparison is with Calacatta: broad, dramatic veining too, but opaque, tougher and fit for a real working surface. If you are after the surface you use every day without a second thought, the comparison is with Dekton or quartz: indifferent to acids, but with no translucency and none of the depth of a living stone. Often the best answer is to bring them together in the same project: the base or the wall in glowing onyx, the worktop in Calacatta or in Dekton.

In our Aprilia workshop, on the Via Pontina between Rome and Latina, we have worked stone since 1976. We choose onyx slabs one by one and we look at them lit before cutting, because against the light the pattern is another thing altogether. Cutting is done on numerically controlled machines with slow blades and cutters, polishing and edges are finished by hand, and the backlighting is designed in the 3D model we show you before the saw touches the stone. The quotation is free wherever you are; in Rome, Latina and throughout Lazio the survey is free too; installation is by our own team in Italy, and we deliver abroad as well, as we did for our Dubai project. The simplest way to begin is to write to us from the contact page with a floor plan or a photograph of the room. The terms of the trade are explained in our glossary; the sequence of the work on the craftsmanship page.

• Marble Kitchen Island: Monolithic, Waterfall, Thickness
• Marble Kitchen Worktop: Thickness, Edges, Finishes, Care
• Poolside outdoor kitchen: stone, finishes and shade
• Outdoor stone bar counter: levels, overhang, stones