Dating waltham pocket watch
lever and pendant set, etc..) and the occasional transcription error.
The original Waltham database is maintained by the NAWCC but the most comprehensive site I have found is The Pocket Watch database.
This is probably the most common question watch collectors have.
Sometimes it is easy to answer, and sometimes it is impossible.
It will NOT tell you the actual date the watch was acquired...
many watches spent years in warehouses before being sold... If there are some letters incoroporated in the serial number (common with Hamilton and Elgin) your watch was probably made AFTER the last date on the chart.
By the late 1930's mens watches were more masculine. This was made possible by the advent of square movements.
These are generally the easiest as for many makes, such as Waltham and Hamilton, production records are still extant and enthusiasts in the US have put a huge amount of effort into putting them into online databases so by taking the serial number of the movement (not the case number!
The Elgin and Hamilton were dated by serial number, while the Gruen was dated by an inscription on the back. In the 1930's there was a style change from highly engraved cases to smoother cleaner lines.
The "New Haven" was dated by looking at the style of the watch. Notice that the watches from the early 1930's still have engraved cases.
For most of the other makes the data is not generally available or, as is the case with Revue Thomman, the movements do not carry a meaningful serial number, just a 2 or 3 digit number to identify watches within a batch of production.
Having had a lot of watches by Cyma and Tavannes I have been able to build up a good database of serial numbers vs date for production between c19 using the silver hallmarks (see below) which is now good enough to identify the date to within a year. Beyond this is comes down to experience and identifying key features such as machine set jewels which determines the earliest possible date.