Gruen dating 1925 to 1957 + the calibers 405, 406, 410, 420, 421, 425, 426

As shown in the picture of this post, there are two usually three-digit numbers in the caseback of every Grün watch

The left one indicates the caliber, the right one is the so-called "style number"

Below, the style numbers of a Gruenwatch are assigned to the years of manufacture of the watch from 1925 to 1957:

Style number Year of manufacture

0      1925
11    1925
55    1926
61    1927
77    1928
79    1929
86    1930
107    1931
123    1932
139 1933
151    1934
182    1935
220    1936
255    1937
304 1938
372    1939
390    1940
449    1941
495    1942
506    1943
512    1944
541    1945
544    1946
553    1947
583    1948
625 1949
641    1950
742 1951
752    1952
832    1953
863 1954
883    1955
933    1956
1015 1957

Source: gruenwristwatches.com

Serial number date table for the Gruen 405, 410, 420 and 425 caliber families

This table applies to calibers 405, 420 and 425 and serves as a guide for determining the approximate date of manufacture of a movement.

It is particularly applicable to calibers 405, 406, 410, 411, 420, 421, 425, 426, and the central second versions. Please note that this table is still in draft form and is subject to change.

Serial number Production year

? 1938
100,000 1939
175,000 1940
250,000 1941
400,000 1942
600,000 1943
750,000 1944
900,000 1945
A 100,000 1945
1A 10,000 1945
1B 10,000 1945
A900,000 1947
B 100,000 1947
B 900,000 1949
C100,000 1950
C800,000 1952