Judging from the pics the coin looks authenic to me. I do not see any red flags that leads me to think otherwise.
As far as reverse being mirror-like and the obversed toned? That sounds like either one side has been cleaned or protected from the elements that caused the toning. Better pics would help. It might be a nice au/unc with just toning on the obverse hiding the brilliant underneath surfaces.
Either way, it looks like a nice type coin and I would not be ashamed to own it.
Did you get it at a good price and are YOU happy with it is really all that matters.