http://www.potsaa.com/vintage-pfaltzgraff/

Does pfalzgraff always have a stamp on he back?
I bought the plates apart from eBay and they were described as vintage pfaltzgraff, pfaltzgraff I have a few others and it is all stamped with the castle.Anyway, it is not and I wonder if they are really pfaltzgraff or not. I am not sure if I should be checked or not. Does anyone know with certainty whether they are still fingerprints? I think they are, but I am not an expert.
Pfaltzgraff is my 80s and it is stamped.