With any natural stone product some basic maintenance and care should be taken to keep the natural beauty of the surface. Stone Countertops are very low maintenance surfaces. Some variations between the particular stones exist but for the most part maintenance is minimal.
The Marble Institute of America recommends cleaning with just warm soap and water and resealing once a year depending on use and the type of stone.

There are good cleaners and sealers available to use for Natural Stones. Be sure to use the ones recommended for your type of stone. Different stones require different care and maintenance.