Dating older seiko 5 serial numbers

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.Here’s an example from 1963, which carries all the information to be found at that time except water resistance – see the labels for their meaning: Notes: 1) ‘STAR’ – as far as I know this the mark of Citizen’s own case factory.It is found on watches from the 1940s through to the late 1960s.6) Serial Number – by 1963 the use of this type of serial number was well established – see later on in the page for information on serial numbers and production dates.7) This example has no indication of water resistance – watches were increasingly marked ‘Parawater’ after 1958 when Citizen designed water proof cases for the first time.The case number is often more useful than the model number, since it usually includes a reference to the movement in the watch.

Variants on this format often have less information than the above illustration.

Acknowledgement – in order to get a uniform type of image and size, I have primarily used the Japanese Domestic Watch volumes as a source, I wish to give due acknowledgement and credit here.

Early Case Backs: This section relates to watches made from around 1950 to the early 1960s.

2) In the above example you can see how the case number relates very clearly to the movement (7200) 3) ‘STAR’ has now been dropped, and the manufacturer’s name is more prominent.

Later watches have ‘Citizen Watch Co’ rather than just ‘Citizen’ As ever, there are variations on this theme – some models, I think only in the Seven Star range, have a ‘horseshoe’ track rather than a full circle, and some backs have no model information – the X8 Cosmotron on the right is marked ‘transistorized’ reflecting the application of new technology, but is not marked ‘parawater’ or ‘water resistant’: Some backs are simpler, with no outer ‘track’ – the Cosmotron on the right below also has a different type of case / model combined number which uses the full movement designation as its first part; it’s also now marked ‘water resistant’ and ‘electronic’ rather than transistorized’: The Seven Star on the left below has the case number in the outer track, echoing the ‘transitional’ format, and on the right a black coated Custom V2 also has a coated back (others had stainless steel backs): Serial Numbers and Production Dates: Dating a vintage Citizen watch is relatively straightforward when it has a serial number on the case back.

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