Pieces like this give themselves away through a chain of inconsistencies, each of which might be explained on its own but which together add up to something that cannot be original. Strikingly fresh imprints on a supposedly very old pen are only weak evidence, since re-whitening the stamping later is common practice. The fittings tell you more: a cap ring of unfamiliar shape and set an unusual distance from the cap lip is not documented for Montblanc, and a star with sharply drawn-out points suggests the Eastern European reproductions known from the Czech Republic and Romania. A clip markedly too small for the cap is another warning sign; on genuine ball clips the metal ball is a separate piece, soldered on, and was never made in one piece with the clip.
The same goes for the barrel: a lever set close to the end of the barrel occurs on no Montblanc lever filler. Particularly revealing is a check of the patent number next to a Simplo imprint, because if that number belongs to a plunger filler, the pen cannot be a production lever filler, and the prototype explanation falls away as well. Not infrequently it is the nib of all things that is genuine, though from a different era, the 1950s say, and therefore at odds with the pen it is supposed to belong to. For checking shapes, caps, cap rings and clips, Rösler's collector books are the best foundation. That over 500 euros was bid for a piece of this kind in 2008 shows how worthwhile the effort is for the forgers.