Dilute 3 tbsp. of standard baking soda in a 1-gallon container filled with warm water. Stir the water to combine it completely.
Dip a soft cloth into the mixture until it is soaked through. Wring the excess water from the cloth.
Wipe down the tabletop with the wet cloth, paying careful attention to any spots of dirt or other marks.
Leave the marble to dry for an hour with the baking soda on it.
Wash off the baking soda residue using plain water.
Sprinkle marble polishing powder all over the entire marble top of the table. Work the powder gently into the marble with a clean, wet cloth.
Wipe down the marble with plain water to remove the polishing powder until the table is clean.
Buff the top dry with a clean towel.