Stewart, are you sure this business about the omission of "chronometre" marking is not just a Roesslerism, made "true" by repetition? I find the markings pretty consistent for the Jobin calibers and after. The large majority of such watches are marked on both dial and movement. In the exceptions where it is not, this statement is always trundled out by the seller to explain the discrepancy but I suspect a replaced movement.
I do find that chronometer marking on the Zenith movements prior to the 133.8/71/135 are scarce. Perhaps Roessler was talking about these and generalized to later movements as well?
Click to expand...