another difference between the 46-47 and the 48-50 is the rings on the top and bottom. the 46-47 has linear vertical ridges in both places; the 48-50 has knurling of the top ring and vertical ridges of the bottom ring, like yours.
Gold plating is made with well varying perfection. For example the gold plating on some watches lasts 50 years while for some it lasts less than 1 year. I don't expect gold plating on a Gillette razor can stand more than 5 years of daily use. (I don't have any gold plated razor as of now, apart from the one I'm expecting to arrive, which is well abused.)
