Advice on refurbing an old, valuable copper pan

Hello Chowhounders,

I've been just reading until now, but I'd love to get your input on something. I have bought an old Gaillard pan that weighs more than 15lb. However, it has a heavy patina from age. I would like to polish it up, but I don' t want to hurt its value. Can you advise? Is there a way to polish it while keeping some if its dark red patina?

Finally, if polishing it won't hurt it, how can I polish it in a gentle way.

Thanks,
Andrew