Allow the mortar to set overnight. After tiling a countertop, you should let the mortar dry according to the manufacturer’s instructions. While it may be only a few hours, waiting overnight ensures that everything is well set when you get back to work.

Grout the marble tile countertop using the grout of your choice. Remove the vinyl natural marble floor tiles spacers. Then, use a rubber float to press grout into the grout lines. Work smoothly and methodically, using a rubber float to spread the grout and wipe up any excess.

Remove excess grout by holding the rubber float at a 45-degree angle and dragging it across the floor tiles in a diagonal direction.

Clean the tiles with a damp sponge when finished. Once the grout is evenly distributed in the joints, clean the grout off the room tile faces using a damp sponge. This should wipe off any residue or grit that got on the wood tiles while installing. Only swipe over the surface of the tiles — do not dig into the grout lines.

Allow the grout to dry before adding a finish to the counter. To protect your onyx tiles for years, you’ll want to apply a finishing solution to the grout. Find a grout and tile sealer that works for you at your local hardware store and apply according to the directions on the bottle.