Clean up spills quickly, before they penetrate the surface.
Clean stone surfaces with a few drops of stone (which can be found at your local hardware store), or mild dishwashing liquid with warm water.
Use soft, clean cloth to clean the granite. Rinse after washing with the soap solution; then, dry with a soft, clean cloth.
Remove a stain on granite, basing the method on the type of stain. Mix a cup of flour, 1-2 tablespoons of dishwashing liquid with water to make a thick paste. Put it on the stain, cover with plastic wrap, and let it sit overnight.
Scrape away the mixture with a wooden utensil and rinse. If the stain is oil-based (e.g. grease, oil, milk), use hydrogen peroxide in the paste instead of dishwashing liquid - or try ammonia on it.
Try a mixture of 12 percent hydrogen peroxide mixed with a couple drops of ammonia for an organic stain (e.g. coffee, tea, and fruit).
Use a lacquer thinner or acetone to remove ink or marker stains from darker stone. On light-colored granite, use hydrogen peroxide to these stains. This also works for wine stains.
Mix molding plaster and pure bleach into a paste and spread over a wine, ink or other non-oil stain. Leave on for 30 minutes, then remove and rinse.
Paste a mix of molding plaster and water over an oil-based or fat-based stain. Mold it into a bird's-nest shape and allow to stand for 3 hours. Remove and rinse.
Reseal the countertop every year or two years. Check with the installer for recommendations. Use a non-toxic sealer on food preparation areas.
Consider using a new disinfectant cleaner made specifically for granite.
Call your professional stone supplier, installer, or restoration specialist for problems that appear too difficult to treat.