You'll have to excuse my ignorance of Chinese coins, but is this worth the price of conservation considering that you will end up with the same details grade? Do you just want to preserve it because it is staying in your collection?
What? They may pay for the coin as well? what? I'm with all those before me--you bought the coin for.....?? your collection? you liked it? Most of the time you can select if you want it preserved etc. what have you..green spots..you bought it? Back to my beer..you keep posting pics..I am learning by the minute (teachmind)???
I somewhat doubt that it's PVC. It looks more like verdigris and they can form on silver coins as well. There's many different varieties of this coin however I am not well versed in this particular type.