I'm definitely not an expert on Belstaff but if it says made in Italy chances are it's real.
I read somewhere that even if they fake everything else, they can't do that with the 'made in' tag for some reason (items not allowed to be exported? fine could be huge?). And most fakes are obviously made in China/India/Thailand, definitely not Italy.
Obviously the seller could have replaced the tag, though...
This is the exact opposite of true.