-----Carrara Penny Marble Mosaic Tile Installation Tip
If you use them as, we recommend our customers to sealed (regular sealer) the marble after grouting, it will protect the tile and keep your grout in tact.
You can use either the sanded or the non-sanded grout, depending on your specific application. But, usually, on polished surfaces, the non-sanded option gives better / nicer results.