The only way to remove a stain from stone is to literally pull it out with a liquid chemical mixed with a powdered poultice. When placed on the stain, the chemical dissolves it, and the powder absorbs it. The list on the left shows the chemicals that work best with common household stains. A Powder poultice is readily made available and sold where ever stone and tile are sold. Look for the kind that are Iron free and haven't been premixed with stain removing chemicals. Before applying a poultice, always clean a stain first with water and pH-neutral stone soap, such as Aqua Mix's Stone Cleaner or Stone Care International's Marbamist. Blot, don't wipe the area dry; then wet it with a little distilled water. Then follow the steps below
Stir the appropriate stain removing chemical (see list on left) into a poulticing powder and make a paste consistency with peanut butter. Apply a 1/4 inch thick layer to the stain (any thicker will dry too slowly) overlapping its edges by at least 1 inch.
Cover the poultice with a plastic sandwich bag or food wrap. Tape down the edges with blue low- contact masking tape. (the adhesive in regular masking tape can leave a stain). Allow the poultice to sit from 12 to 24 hours.
Remove the plastic and let the poultice continue drying. Once it's bone dry, scrap it off, throw it away, and rinse the area with distilled water.
If the stain is gone, let the stone dry and apply a sealer. If any sign of the stain remains, repeat the poultice process. If stain isn't gone after five tries, call in a stone specialist.