Opinions Wanted: Copy? Metal Bubbling?

I'm not certain what to make of this coin. It appears to have outermost layer of metal bubbling off of the center core. Whether or not this is a copy or not is what I am looking to learn here. It is suspicious enough that I have no intention of bidding on it and it is just an ugly coin regardless with the pockmarks from metal blistering off of the center. Anyone familiar with this? I'd like some advice. I'm trying to learn as much as I can and get as good as I can get at identifying copies of Russian coins (since they are so prevalent) by sight alone so as I work on Ebay, I can avoid as many counterfeits and lost money as possible.
Thanks for the opinions everyone!
1791 Grivennik
Thanks for the opinions everyone!
1791 Grivennik
0
Comments
somebody cleaned off the green verdigris and now (once again) offered as solid 900/1000 silver.