I have sealed, polished marble surfaces on my end tables and coffee table. Marble surfaces should never be cleaned with generic cleaning products because the acid or alkili with dull the polish over time, even if they're sealed. This is known as etching.
Method Daily Granite is a non-toxic, biodegradable granite and stone cleaner that's safe to use on marble as well as on any other stone surface. The active cleaning ingredient in Method Daily Granite is alkyl polyglucoside, which is made from corn and coconut oil, and the neutral pH balance gently buffs a marble surface without etching it. I like the fruity scent of Method Daily Granite. I just spray it on my end tables once a week and wipe it off with a soft cloth. The bottle is made out of 100% recycled plastic, and I'm personally impressed with just how well that turned out having grown up in the plastics business. A 12 ounce bottle of Method Daily Granite cost about $5.50 at my local grocery store, and I really had to search the cleaning supply aisle to find it. But Method Daily Granite is worth seeking out if you have any stone surfaces to clean in your house.