Start with what is wrong.
Tap the one that looks like yours for a straight answer on whether it comes out in place.
Etch marksDull spots, rings from glasses, a matte patch where lemon or vinegar sat.StainsA dark patch that has gone into the stone. Oil, rust, wine, something that sat too long.ScratchesFine lines that catch the light, usually all running the same way.DullnessThe whole surface has gone flat, so it reflects nothing and cleaning makes no difference.Failed sealerHazy, blotchy, or water soaks straight in instead of beading.Chips and cracksA piece missing from an edge, or a line running through the stone.