I think to polish marble countertops you need to buy flexible diamond polishing pads. Diamond wheels are suitable for wet and dry cutting. I recommend the manufacturer NovoAbrasive https://novoabrasive.com/en/diamond-polishing-pads. The polishing wheels are made of high quality resin-impregnated diamond powder. With this tool, you can polish not only marble, but also granite, concrete, tile, stone. I always stock up so I don't have to order often.