Hi! I am helping provide information to unanswered questions from the past. Please disregard this comment if/when the original picture owner answers the question.

I have successfully removed stains with a poultice by aqua mix or stain remover by DuPont.

It may also be possible that you have etching of the surface witch can be remedied with a re-polishing.



Sincerely,

M&C

That's not a stain. It's etched. That's permanent.