The smartest way to prevent stains on your marble is to treat the stone with a protective sealer. Sealing your marble is a critical step in the marble restoration process. Once you've had your marble polished and restored, it's wise to seal or impregnate the marble. Keep in mind that marble is formed over millions of years. And yet one spill or stain can instantly ruin the pristine finish.
Marble is a porous stone, and therefore stains can easily occur because the staining substance is absorbed into the marble. An impregnator, or sealer, works by filling in the pores of the stone that naturally exist which repels spilled substances. If possible, quickly blot the liquid substance using a terry towel. If your stone is sealed, the substance won't have a chance to stain the marble.
Considering the location and usage of the marble is helpful in deciding whether to use sealer. Sealing your marble may result in a slight enhancement, or darkening, in the color of the marble. It is highly recommended that marble floors and marble vanity counters be sealed. Only a few ounces of sealer are needed to protect your marble for years to come.