Mark, thanks, but no expert here..Just an enthusiast like yourself. I just happen to have been looking into Z. marks last year for my project...
There's plenty of fake 3rd reich silver. All stamped up and ready to play..I can just make the comment that the Z. marks I've seen have had a special content mark as well, and,,an art deco looking 'Berlin' on the larger pieces. Doesn't mean its always like that though..
Best bet,find some original pieces about the same size, year and start your comparing!
