Marble is a porous material, so it is easy to stain. Experts recommend using less water when cleaning.

The correct method: regularly wipe with a slightly damp cloth with a mild detergent, and then use a clean soft cloth to dry and polish. The seriously worn marble furniture is difficult to handle. It can be wiped with steel wool and then polished with an electric sander to restore its luster.

Using lemon juice or vinegar to clean stains is also a good way, but it should be noted that the lemon juice should not stay longer than two minutes. Repeat the operation if necessary, then wash and dry. For minor scratches, special marble cleaners and care agents can be used.

When the marble is stained with fruit juice, coffee water, beverage, nicotine, and other stains, wipe it off with a few drops of vinegar detergent and rinse it off with clean water after wiping. To remove the soot on the marble, you can scrub it with soapy water. Use gasoline to wash away the grease on the marble. When the marble is stained with ink and other stains, add a few drops of ammonia to 20 parts of water to one part of hydrogen peroxide, wipe with a soft cloth dipped in this solution, and then wipe it dry with a soft cloth.

Source: https://www.unisun-groups.com/what-method-can-be-used-to-make-the-marble-as-bright-as-new/