Have used slightly moist rag with lacquer thinner for this also.

On Wed, 22 Sep 2004 08:50:00 -0700, David wrote:

My dad recently called me to inquire about the best way to remove a
water ring from a piece of fine furniture. I suggested dampening (NOT
soaking) a rag with denatured alcohol and wiping the ring lightly
(circular motion) a number of times. The correct amount of alcohol is
that which leaves a slight trail as you move the cloth over the marred
area. He reported back that the ring disappeared...

David