People often assume that natural stone is "stain-proof," however all stone is porous to some degree. If not properly treated with a protective sealer, water, oils or other liquids can easily penetrate the stone, leaving behind unwanted stains.
The good news is that once treated with a protective sealer, natural stone is ready for carefree, everyday use. Sareen Stone recommends DuPont^TM StoneTech Professional® Stone Care Products.