No real importance where the lens comes from: it is absolutely impossible to prove if a ZK without Zeiss numbers is a fake or not.
We know that KMZ received Zeiss parts (and complete lenses too) from Germany.
We suppose they used it regularly: complete lenses first, then spare parts. And of course, these German parts had to be completed by Russian ones.
But we don't know for sure when it occurred, nor for which lenses first, nor for which parts, nor for which mounts.
I think that a 1950 (or perhaps even 1949) LTM 4/13,5cm Zorki can be true without Zeiss number. But a 1950 1,5/5cm Jupiter certainly will be a fake without this Zeiss number. And for the ZK/Jupiter 12, all can be true until 1952, with or without Zeiss number from 1950... As for the ears, sure the Jup 3 and 8 should have them until 1950.
Certainly, all that is very complex. And when we buy such a lens, we must be prepared to think of a possible fake. And of the possibility of re sending it if it does not seem "square".
All that is only what I think, after having examined closely dozens of these lenses. But there is no rule: as I have already said, I own a Jupiter 3, dated of 1974 by KMZ, and with a Zeiss serial number on the back...
Amitiés. Jacques.
