More and more watches were using screw on backs and less were using the snap on type more typical of the early model ranges.
Case design was also developing and other case types were emerging.
Not all watches had a serial number at this time, although sometimes they may be found stamped inside the case back.
And not all case backs carried all the markings – some were minimally stamped and very simple whilst some were decorated, often with scrolled engraved lines.
After looking at a fully marked example, I’ll show some of the variations.
The case number is often more useful than the model number, since it usually includes a reference to the movement in the watch.
So for example, case number 4-520343 tells us that a movement from the ’52’ family is used.
Case numbers always start with the number ‘4’, followed by a dash and six other numbers i.e 4-123456.
With the new case number system, a new model number format was also instigated: 12-3456.Model names are not often seen on the back, but some now indicate the movement to be found inside – this is very helpful of course!Here’s a typical example of a fully marked back: Notes: 1) I have not been able to determine the system, if any, for model numbers – they generally do not help to identify the movement used.2) ‘CGP’ – this is the Case Material Code – often this is an abbreviation, and is usually self-explanatory as in this example (Citizen Gold Plate).Some gold plated and especially gold filled watches specified the thickness of the gold, in microns.‘Parawater’ continued until the early 1970s when it was replaced by ‘Water Resistant’.