Two weeks later, in fact this past weekend, I was at an estate sale and found a charming little antique plate which was heavily discolored for only $2 (see picture at top of the post). I remembered Meg's recommendation and decided to give it a try. It took about 10 hours soaking in the oxi-clean but look at the results; nearly perfect!
I'll be trying oxi-clean now on a number of other items; Thanks Meg! By chance, does anyone recognize the maker's mark on the back?
I received no compensation from oxi-clean (in fact I had to pay a premium in order to buy at my local drugstore!)