Някаква идея дали е истинска?

It looks like a cast fake to me.

Как да разбера дали е истинска или не е?  Размерите и грамовете са почти едни и същи?

It gives an appearance of being cast because the details are very soft, apart from some of the lettering.  But it is possible that that is due to how it is preserved, but there are reasons to be suspicious.    You can check the edge of the coin, and see if there is evidence of a seam.   

Because it is such a notable type forgeries of these are made a lot.  If it is a cast fake the weight and size would be expected to be correct.  

Не няма шев на ръба гладък е