Both onyx and marble are natural stones made of calcium carbonate — but their different characteristics affect how easily they can be repaired.

Marble Repair

Marble is one of the most repairable natural stones. The range of marble repair compounds available, the relative softness of marble (which makes shaping repairs easier), and the extensive professional experience with marble repair all contribute to consistently excellent results.

Carrara, Calacatta, Statuario, Nero Marquina and most other commonly used marble types are well within the capability of an experienced technician. Veining is matched and continued through the repair area.

Difficulty: moderate — veining matching requires skill but is well-established practice.

Onyx Repair

Onyx shares marble’s calcium carbonate composition but presents additional challenges — its semi-translucent quality means that a repair that is opaque will be visible where the stone is backlit. Specialist transparent compounds are required to replicate the translucency.

Onyx’s distinctive banded appearance also requires careful colour and pattern matching.

Difficulty: higher than marble — the translucency requirement adds complexity.

The Verdict

Both are repairable to a good standard. Marble is more straightforward and results are more consistently invisible. Onyx repair requires specialist approach and results are highly dependent on the specific design and lighting conditions. Send photos for an honest assessment of either.