Wipe away any water that’s still there with a paper towel or absorbent cloth.
Spoon a generous amount of mayonnaise onto the water mark and rub it in with your fingers or a paper towel.
Allow the mayo to remain on the water ring for at least an hour.
Wipe off the mayonnaise with a paper towel. The ring should be gone. If it's still visible, apply more mayo and leave it on for several hours or overnight.
Add baking soda or ashes to some mayonnaise if you can still see any of the water ring. Cigarette, cigar or fireplace ashes will do. These items all add a touch of grit to the mayo. Use a damp cloth to gently rub the mixture onto the water rings. Let stand for several hours and then wipe away.