Natural stone
Onyx
Onyx is the most theatrical of the natural stones we work on. Formed by slow mineral deposition from cold groundwater, each slab is built up over thousands of years in thin, wavy bands of calcium carbonate. That is what gives onyx its ribboned grain, its translucency, and its one-of-one character. No two slabs are the same, and because onyx is often backlit, even small imperfections in the stone, the resin fills or the surface finish become very visible in situ.
Common varieties we restore:
- Honey Onyx, the classic warm amber tone, popular in hospitality bars, spa counters and feature walls.
- White Onyx, delicate cream with fine grey or gold banding, usually specified for residential vanities and backlit panels.
- Green Onyx, richer, often near-jade, popular in art deco bars and reception counters.
- Red and Rosso Onyx, dramatic cognac through to deep burgundy, frequently seen in London private members clubs.
- Blue and Azure Onyx, rare, cobalt through teal, used almost exclusively as a feature element.
- Black Onyx, deep obsidian with fine white banding, most often in bathroom vanities and high-contrast bar tops.
Onyx is calcium carbonate, so chemically it behaves like marble: it etches when it meets an acid. The difference is how quickly and visibly it shows the damage. A splash of wine on a backlit honey onyx bar will not just leave a dull ring, it will interrupt the way light passes through the slab. That is why onyx restoration is as much about optical consistency as it is about the physical finish.
Our onyx work in London divides into three broad patterns. First, hospitality restoration, typically bar tops, reception desks and private dining counters, where daily exposure to citrus, wine and cleaning products creates a steady pattern of etching and micro-scratching. We restore these under a strict out-of-hours protocol, with dust-controlled diamond honing, optical polishing of the banding, and a breathable sealer chosen for food-and-drink surfaces. Second, residential restoration of private bathroom vanities and feature walls, where the brief is usually to return a backlit panel to even transmission of light, with all existing resin fills refreshed and re-matched to the veining. Third, heritage restoration on period onyx fireplace surrounds and staircase inlays, where the work is slower, more conservation-led, and carried out alongside other listed-property trades.
Because onyx is softer and more brittle than marble, we do not use the same aggressive diamond sequence on it. Pad choice, pressure and cooling water are all adjusted to match the specific variety. Marius surveys every onyx project personally before a quote is written, and we do not subcontract any part of onyx restoration.
Services we offer for onyx
- Onyx polishing calibrated for the softer, more brittle stone
- Stain removal on bar tops and vanity surfaces
- Crack and chip repair with colour-matched veining fills
- Sealing and impregnation with food-safe breathable sealers where needed
Characteristics
- Translucent or semi-translucent, which is why onyx is often lit from behind in bars, reception counters and feature walls.
- Formed by slow mineral deposition from cold water, producing its signature curved, ribbon-like banding.
- Colour palette ranges from honey and amber to green, cobalt, deep red and near-black, with each slab effectively one of one.
- Softer and noticeably more fragile than marble, prone to micro-fracturing if mishandled during installation or cleaning.
- Calcium carbonate base, so it reacts to acids (wine, citrus, vinegar, many household cleaners) and will etch on contact.
Common issues
- Surface etching from acidic drinks and cleaners, especially common on bar tops and hospitality counters.
- Hairline micro-fractures along natural banding, sometimes widened by thermal shock or point impact.
- Dullness from abrasive cleaning pads or general wear in high-traffic settings.
- Backlight hot-spots or cold-spots when the original resin fill starts to yellow and block the translucent bands.
- Water staining and salt efflorescence if a bar or vanity onyx was not sealed before commissioning.
Care guidance
Use only a pH-neutral stone cleaner, and always a soft microfibre cloth. Never vinegar, lemon, bleach or supermarket descalers. Blot spills straight away instead of wiping. Re-seal every 12 to 18 months on a worktop or bar top, every 2 to 3 years on a wall or decorative panel. Avoid placing very hot or ice-cold items directly on the surface.
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