Removing Silver Discoloration from Gold Jewelry: Causes & Solutions

Question
I accidentally put an old coin in my jewerly cleaner and then when I put my 14K gold jewerly in it, it turned silver.  Is there any way to get it off?  My jewerly said he couldn't polish it off because of all the pores.  He couldn't get it off with any of the acids in his store either and couldn't give me anywhere to take it either.

Answer
Not sure what happened here....what was the coin made of? silver sterling or base metal brass??? the chlorine or ammonia reacted with the coin metal and left a residue on your gold jewelry....it CAN be polished or placed in Sparex which is a cleaner for gold ONLY after chains or rings are soldered or sized. It may take over night to do this....take it to a jewelry store with a shop and have them buff the item with a coarse tripoli or some other rouge used for platinum...usually these types of compounds are more coarse and should work....send me a picture so I can comment further.
all the best
Les