Ok, JG, here's the first thing to try. If you're a smoker or know someone who is, you need a quantity of cigarette ashes. Plenty. Made a thick paste of the ashes and water and put the paste on the ring. Let it sit for at least 12 hours, then wipe them off with a damp cloth. Follow that with a good rubbing of lemon oil, then a good paste wax.
If you don't have access to cigarette ashes, you can use a paste of baking soda.
It may take several applications to make the ring go away and, still, it might not be completely gone, but quite invisible.
This is the first thing that comes to my mind. When I go to the shop today, I'll check my resource books there and see if there's anything else I can suggest.
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!