Dating a Pocket Watch by Its Serial Number

Four makers whose movements can be dated from the number engraved on the plate, on one page, with the caveats that go with each. We use these on the bench; they are compiled from the published factory lists and, for Longines, from the factory's own ledgers. The year beside a number is the year that block of serials began. A movement could sit in stock for a season or for years before it was cased and sold, so read every result as "made in or shortly after".

Before you look anything up

Elgin National Watch Co., Elgin, Illinois, 1867 to 1956

One continuous sequence across every grade and size, from No. 101 in 1867 to 55,000,000 in 1956, which is what makes a single table possible. The company is signed Elgin Natl. Watch Co. or simply Elgin on the movement throughout. Grade and model are separate matters and are not encoded in the serial.

American Waltham Watch Co., Waltham, Massachusetts, 1852 to 1957

Compiled from the factory's printed serial list, the so-called Gray Book of 1954, and the surviving handwritten ledgers, which the NAWCC has digitised. The company name on the plate is a second check: American Watch Co. to about 1885, American Waltham Watch Co. from about 1885 to 1907, Waltham Watch Co. from 1907. A movement whose name and number disagree by twenty years almost always means the case number has been read by mistake.

Omega, Bienne, 1895 to 1970

Omega published only milestone figures, one line per million or so, which is why this table is coarse. Between two lines, interpolate. The serial is on the movement, usually on the barrel bridge or under the balance; from the 1940s it is sometimes under the dial. Numbers below one million belong to the pre-Omega Louis Brandt et Frère era and are not covered here.

Longines, Saint-Imier, 1867 to 1969

Longines kept a handwritten ledger entry for every movement from No. 1 in 1867 to No. 15,000,000 in 1969, and the figures below are taken from those records rather than from the internet tables, several of which are wrong by a year or more. Up to 15,000,000 a complete watch left the factory with the same number on case and movement; uncased movements sold to the American agent carry the factory number on the movement only. The month is given where the ledger records it.

Zenith, Le Locle

We do not print a Zenith table. The two serial lists in circulation disagree with each other by three to four years across the pocket-watch era, and Zenith itself notes that movements could wait many years in stock before casing. A Zenith is dated from its calibre, its case hallmarks and, where it matters, an extract from the Zenith archives, which is inexpensive and definitive. If a reliable ledger-based table is published we will add it.

Sources

Elgin: the factory production list as reproduced by the NAWCC and the Elgin collectors' databases. Waltham: Serial Numbers With Description of Waltham Watch Movements (Waltham Watch Co., 1954) and the NAWCC Waltham serial database. Omega: the milestone list published by Omega and reproduced in the standard references. Longines: factory ledger figures published by David Boettcher (vintagewatchstraps.com) after a visit to the Saint-Imier archive. Corrections welcome.