Well,, I can tell you what you probably already know... This is a good known pattern, also that It has been copied for a long time and its one of the rings I was tricked on in the late 70s..[think I still have it].. Some of the newer counterfeits of the last 20 years have been very good...

Originals have been unstamped and stamped. Period advertisements just list them as in Silber... Can you get a better/clearer shot of the content mark?