Is there a rough date from which point on Zenith started using signed crowns? Or?

 

Maybe very late 40's - early 50's. My feeling is that most everything after 1950 should have a signed crown, though I'm not sure about some models, e.g. early S.58's.

 

The earliest one I have with a signed crown is 1953 but who knows what is original and what isn't with earlier Zeniths?

 

Agree, likely early 50's. Signed crowns are very rare on earlier models, to the extent that I think they are likely all later replacements.

 

Thanks, that's more or less what I suspected from looking around.

 

I think the signed crowns (Z-in-Star) start with the stellina, the little applied star at 12 o'clock on the dial... so I don't expect earlier watches without applied stars to have signed crowns.

 

Good point, makes sense.