According to DoItYourself.com, marble countertops can safely be painted for a nice re-finished appearance. While marble countertops often start as shiny, they can lose some of their brilliance to wear and tear over time and may require re-finishing.
In order to re-finish a marble countertop, it is recommended that the countertop first be cleaned. It is also best that any scratches or blemishes be repaired on the countertop before it is painted. To avoid scratching the marble countertop, it should be cleaned with a soft bristle brush. Once the countertop is clean and free of hard stains and/or scratches, the next step is to tape the edges of the countertop and start painting.