We have a ring around our bathroom sink. I was thinking it was a water stain but we have let it sit for a bit with the water turned off under the sink and it isn't fading.. I'm thinking maybe it is some of the products we use to wash our face? Could it be oil? Is it a water mineral stain?
I've tried heating it with a cardboard tent to try to "dry it out" but it looks to be something else..
The picture shows it pretty well..