Dry the area thoroughly with paper towels.
Dry the damaged area with a hair dryer set on low. Keep the dryer in motion. The goal is to dry the finish, not to cook the underlying wood. Applying too much heat can cause the finish to crack and check.
Apply furniture polish to the finish as soon as the water spot disappears.
Squeeze a small amount of toothpaste on a cotton cloth. Use white toothpaste only; gel or liquid tooth cleaning products will not work.
Rub gently until the spot disappears.
Wipe the surface clean with a soft cloth.
Pour enough lemon oil on the surface to completely cover the stain.
Rub the stain with very fine, 0000-grade or finer, steel wool until the stain is no longer visible.
Buff the area with a soft cloth.