The first step seals the surface with a special stone sealer. This step will help to prevent acid etching and staining.
In the second step, first of all, you have to apply a special onyx cleaner, such as gel gloss on a soft cloth. Then wipe it on the onyx surface.
The third and last step is to blot up any spills using a paper towel. Be careful do not wipe or apply pressure.
SK Stones advises you to seal and clean your onyx countertop often!