Removing stains from marble, granite and other Natural Stones can be difficult. There are, however, several protective measures you can take:

Any spill should be cleaned as soon as possible. Blot spills with a paper towel or clean whit rag. At this point, it is important only to blot, wiping a spill may spread it over a larger area, making a bigger mess. Use only cold water and stone soap or a neutral cleaner. Wash the area several times. If a stain is still present, a chemical poultice may have to be applied.

Avoid using chemicals of any kind until you know which chemical cleaner to use. See Chemical Chart. Certain chemicals will react with the spilled material and could make the stain permanent.

Natural Stones are porous materials, if not thoroughly sealed, they will stain. The only way a stain can be removed is to literally pull it out of the stone or ceramic with both a chemical and material that will absorb the stain. This chemical absorbent-material combination is what we call a Poultice.

Poultices are usually powder or cloth materials that can be mixed with a chemical and placed on top of the stain. Clays and diatomaceous earth are safe and widely available, but do not use whiting or clays containing iron with an acidic chemical; iron will react with the acid, and may cause rust staining. It is best to purchase powders that are designed specifically for stone and tile. Consult a stone restoration specialist or your stone supplier (fabricator) if in doubt.

Poultice materials you could use:
Paper towels
Cotton balls Gauze pads
Talc Chalk (whiting)
Diatomaceous earth
Methyl cellulose
Flour
Saw dust
Here are instructions on how to apply a poultice:
Before you attempt to remove a stain, it is extremely important to know what has caused it. If you don't know Consult a stone restoration specialist or your stone supplier (fabricator).

Clean the stained area with water and stone soap. Remember to blot rather than wipe.

Pre-wet the stained area with a little water. Distilled water is recommended.

Choose the chemical to use for the stain.

Mix the poultice material with the selected chemical. Mix until a thick (like peanut butter) paste consistency is obtained.
Apply the paste to the stained area, overlapping the stain by at least ¼". Do not make the application too thick, or it will take a long time to dry.

Cover the paste with a plastic sandwich bag or food wrap. Tape the plastic using a low-contact tape.
Allow the paste to sit for 12–24 hours.

Remove the plastic cover and check to see if the paste has dried. If it has not, allow it to sit uncovered until thoroughly dry.

Once it is dry, remove the paste by scraping and rinse the area (use only wood or plastic scrapers).
Examine the stain. If it still remains, but is somewhat lighter, re-poultice until it is gone. If the stain refuses to disappear completely, call a stone specialist.