I am sure you have a buffing machine! Use wet/dry emery paper under your buffer
starting with grit 120 and finishing with grit 600. Finishing the last stage using polishing powder or vitrifying chemical to get a good shine. You can get the powder or chemical from DIVERSY or get in touch with 3M to get diamond polishing pads. This is a very easy process and dont be afraid to experiment, its not rocket science technology, just common sense. Like wise look up and get technick from UTUBE.