Marble, Travertine and Onyx are porous stones that can absorb liquids, which can cause discoloring and staining. To reduce stains on stone sinks caused by liquids, don’t let standing water accumulate as it may soak and leave watermarks. We recommend you to clean your natural stone sink regularly with warm water and a neutral cleaner. Avoid acidic substances (lemon, vinegar, etc.) as they may dull or stain the stone.
It is also important to seal your natural stone sink every 6 months to prevent staining. Stone sealers can be found at home improvement retail stores.