Please post other photos that show the whole ring.
With an RZM stamp on it, I would say it is unlikely that it is original.
Searching for anything relating to, Anton Boos, 934 Stamm. Kp. Pz. Erz. Abt. 7, 3 Kompanie, Panzer-Regiment 2, 16th Panzer-Division (My father)
Initial impression=not good. Is a rule of thumb that Most rings should be marked inside the shank. To stamp them After they have been soldered into a ring would damage them-that is why they are generally stamped while flat and unformed, and unsized- pre-soldering. Is just the way you make rings.
"Much that once was, is lost. For none now live who remember it."
Hi and welcome to the Forum.
Just the RZM stamp alone would be enough
to put me off.........
Yes, the RZM-mark says it all.
Just for clarity: It's note even about the location or the look of the RZM marking. It's mere presence is enough, as there was no so such thing as an RZM-marked ring of any kind.