Stu's idea is good, but almost a guarantee that the stain will be removed, would be to hone the area with a 120 electroplate diamond first, use 40 % peroxide and put a poultice of several white paper towels, or a white small towel or even diatomaceous earth, or baby powder as the material for the stain to wick up in. Pour more peroxide to thoroughly saturate the material and cover for 24 to 48 hours. Remove the plastic cover and leave the material on the spot to dry out for another 24 to 48 hours. Finally bring up the area to the polish level of the surrounding area. I have found that when I hone the area first, the chemical agent can more readily be absorbed and the stain can be pulled out quicker and easier.
Best Regards,
Randy Frye, CEI Surface Pros
239-253-1991