Serial Number: The serial numbers on modern Seiko models are comprised of 6 digits. The first digit indicates the year, the following character the month and the remaining 4 digits a unique production number. The month is listed as 1-9 for January to September, then 0 for October, N for November and D for December. Seiko watches have a 6 or 7 character serial number on their casebacks. The second character can be a letter but the rest are all numbers. You can use the Seiko serial number in conjunction with the movement number to calculate the year of manufacture. All Seiko's should have a Serial number on the case back The first number in the Serial is the last number in the year of production, and so if it is a new watch and you see an 8 it should be the year 2008 The second number in the Serial is the month the watch was made if you see a 4 it will be the month of April.
This page is dedicated to my studies on production numbers and -timeframes of Seiko Vintage Dive watches. Model series
included in the study cover the automatic 300 m models as well as the 'classic' 150 m divers (6217, 6105, 6306 and 6309).The first part deals with the distribution of my current data set, then for the first time I will publish some results on absolute production numbers and eventually a timeline of the manufactured models.
Seiko Serial Number Lookup
Distribution of the data set
Caseback data were stored in the format of pictures with calibre, case, subcase, factory code, YYMM and serial number contained in the file name. Data were imported and analyzed with MS Excel. Data source for the divers watches: eBay (approx. 85 %) and various watch fora (approx. 15 %).
As of August12 2012, the archive contained a total of 1570 caseback pictures of divers watches, figures 1 and 2 show the distribution of the data set per movement (figure 1) and for movement/case/subcase combination (figure 2).
Figure 1Caseback data were stored in the format of pictures with calibre, case, subcase, factory code, YYMM and serial number contained in the file name. Data were imported and analyzed with MS Excel. Data source for the divers watches: eBay (approx. 85 %) and various watch fora (approx. 15 %).
As of August12 2012, the archive contained a total of 1570 caseback pictures of divers watches, figures 1 and 2 show the distribution of the data set per movement (figure 1) and for movement/case/subcase combination (figure 2).
Seiko Serial Number Location
Figure 2
Absolute Production Numbers
This is the first time I try to publish some figures on the absolute production numbers of the series I study. At this stage, I can only present data on watches with the 6-digit serial numbering system, I have not yet found a way to interpret the 7-digit that makes sense to me. Furthermore, it must be clearly noted that the data in my archive are not yet at all sufficient to allow an accurate determination of absolute numbers. The data I will present are thus to be interpreted as ballpark numbers but in my opinion are (1) the best data available so far and (2) should give at least a good impression of which numbers we are dealing with beyond orders of magnitude.
Data for 6-digit watches are thus are based on the following assumptions:
Seiko Serial Number Search
- Each case/subcase combination has an own serial number (e. g., separate serial numbers for 6309-7040 vs. -7049).
- Serial numbers are reset once a month, first watch produced carries serial number YM0000
- Each Factory code has an own serial number (if thus watches were produced in two different factories within the same month, both factories applied their own serial number)
- All cases were built into actual watches
Results are summarized in table 1 and figure 3:
Table 1:
Seiko Serial Number Look Up
Production Timeframes
The evaluation of production timeframes was fairly staightforward, the dataset was analyzed for minimum and maximum YM combinations per model. The evaluation was only done on a case, but not subcase level (i. e., 6309-7040 and 7049 are evaluated together) in order not to clutter up the already busy graph.
Results are depicted in figure 4, the lines represent the production timeframe for each model, production start/end are indicated in in YYMM format.
The evaluation of production timeframes was fairly staightforward, the dataset was analyzed for minimum and maximum YM combinations per model. The evaluation was only done on a case, but not subcase level (i. e., 6309-7040 and 7049 are evaluated together) in order not to clutter up the already busy graph.
Results are depicted in figure 4, the lines represent the production timeframe for each model, production start/end are indicated in in YYMM format.
Conclusion and Outlook:
This study gives a first impression about the absolute production numbers of Vintage Seiko divers watches. The data are however to be interpreted with care and to be assumed as the minimum: as further data become available, the numbers will definitely increase and become more accurate.
The data shown on production timeframes are assumed to be fairly accurate but might also slightly change with the addition of new study material.
This study gives a first impression about the absolute production numbers of Vintage Seiko divers watches. The data are however to be interpreted with care and to be assumed as the minimum: as further data become available, the numbers will definitely increase and become more accurate.
The data shown on production timeframes are assumed to be fairly accurate but might also slightly change with the addition of new study material.
Seiko Serial Number Dating
All Seiko's should have a Serial number on the case back
The first number in the Serial is the last number in the year of production, and so if it is a new watch and you see an 8 it should be the year 2008
The second number in the Serial is the month the watch was made if you see a 4 it will be the month of April
most Seiko serial are 6 digits long and so a serial of 86XXXX would be a watch made in April of 2008
The key to the whole trick is knowing what movement is in side and older movement like the 6309 was made in the late 70's and 80's and so a watch with 86XXXX would be April 1988 and so on ...
A note on months since only one numberis used for the months Oct / Nov / Dec being two numbers is noted by letter
if you see a Zero it is a letter O for October N= Nov D= Dec
8DXXXX would be December 2008 8OXXXX would be October 2008
It does help to know a little about movement production dates when dating watches on the street but if you have a computer handy you can always drop by these fine websites:
Seiko Watch Production Date Calculator
http://www.csce.uark.edu/~jgauch/tools/seiko.html
Seiko production date finder
http://speedtimerkollektion.com/images/ ... finder.htm