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So, you’ve just purchased a used or new Seiko watch. Congratulations! Have you ever wondered when your watch rolled off the assembly line at the factory? In other words, when was it manufactured? Questions relating to the production date of Seikos frequently pop up in various watch forums from time to time.

Well, in case you didn’t know this, the answer to this question actually lies in the set of numbers that are etched or printed on every Seiko watch made. Chances are if you ask watch store assistants when that particular Seiko watch you’re interested in buying was made, you’ll get a blank expression from them. Either that, or they’ll come up with an excuse for not knowing by saying that it’s a new arrival (yeah, right!) 🙂

You can’t really blame them for not knowing because watch sellers are in the business of selling watches, period. From my experience many Seiko dealers aren’t watch enthusiasts themselves. They’re more interested to get a sale from you rather than discuss the history or significance of that Seiko watch that you’re looking to purchase.

Well, I’m a firm believer that knowledge is power. And if you have that knowledge, you have an edge over the seller that could be very useful. Especially when it comes to bargaining for a better price for that new, old stock (NOS) Seiko that caught your fancy.

File photo of a typical watch store in Kuala Lumpur. Chances are that the female store owner in the picture doesn’t even know when the Seiko watches in her shop were made, 🙂

If the store owner senses that you know more about that watch than he or she does, there’s a good chance that you can bargain for a more realistic price. I have gotten a few discontinued Seikos in this manner, saying "Hey look, this watch is eight years old! It can’t be worth the price you’re quoting me!"

Fortunately for me, the watch dealers relented to my counter offers and I got them for the price that I wanted.. They probably figured out it’s better to sell off the watch now than risk their capital tied up in old stock that nobody else is interested in.

Let’s find out how to date your Seiko watch and I don’t mean socially! 😉

Where to look for the serial number

To locate the serial number, you’ll need to flip over your watch and examine its caseback. Seikos with solid casebacks (plastic, stainless steel or titanium) will have the 6-digit serial number etched in a straight line. Those that come with glass display backs like modern Seiko 5’s have the numbers printed horizontally on the glass display back but the numbers are usually faint and difficult to read.

Higher end Seikos with display backs, like the 6R15 caliber Premier or 7L22 Sportura for example, have the serial number engraved not on the glass but on of caseback’s rim.

Here are three examples of Seiko casebacks depicting their serial numbers.

Type I: Seiko 5 glass display back:

Basic Seiko 5 models made from the year 2002 onwards have clear glass display backs as you can see above. The 6-digit serial number is always located at the opposite end of the "SEIKO" text. The numbers are faintly stamped from the inside of the glass. You’ll have to tilt the caseback towards the light to read the numbers properly or better still, use a magnifying glass. The Seiko 5 in this picture is from February 2004.

Update: Some very recent model Seiko 5s have the serial number printed not on the glass but along the caseback rim. If you can’t see the serial number on the glass, then look for them on the caseback rim (usually located on at the bottom part of the caseback).

I guess Seiko decided that it’s easier and cheaper to produce spare display backs without having to etch the serial number individually

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Type II: Display backs on higher end models:

In more expensive Seikos with glass display backs like the Premier 6R20 pictured above, the serial number is usually found engraved along the rim of the caseback. Unlike the rest of the identifying text, the serial number is printed in a straight line. Why doesn’t the serial number follow the curvature of the rim? I’m not sure but I think casebacks are manufactured en masse and the individual serial numbers are stamped on later prior to packing and shipping from the factory. Anyway, the Premier pictured above was made in August 2007.

Type III: Solid metal caseback

The majority of Seiko watches come with solid metal casebacks (stainless steel, solid gold, gold plated or titanium) and the serial numbers are also stamped in a straight line. Pictured above is a the caseback of an SKX007K Seiko dive watch. Reading numbers off solid metal casebacks is pretty straightforward. The Seiko diver above is from November 2003.

How to the serial number works

Every Seiko watch manufactured is given a 6-digit serial number. There are however exceptions to this rule. Seiko watches made prior to the late 1960s, most probably 1967 have 7-digit serial numbers instead. Limited edition models with unique sequenced numbering, e.g. 123/300 (denoting the 123rd piece out of a total of 300 pieces) usually don’t have serial numbers.

Limited edition Seikos are usually made within a very short time frame – perhaps not more than a few months in the year it was introduced. In this case you’ll need to know the intimate history of the model – for example, the SBDX005 Historical Collection 600m diver was released in 2000 with 1,000 pieces made. You may not know the exact month the watch was made but suffice to say, the production year couldn’t be any later or earlier than 2000.

To simplify things, I will use the 6-digit serial number convention. This table below describes the structure of the serial number.

Digit Position Description Characters used Notes 1 Production year 0 to 9 Denotes the year in the decade, not absolute year 2 Production month 1 to 9, "0", "N" and "D" 1 to 9 denotes months of January to October. "0", "N" and"D" denotes October, November and December respectively 3 Sequence number, thousands 0 to 9 The last four digits represent the running number of the watch 4 Sequence number, hundreds 0 to 9 5 Sequence number, tens 0 to 9 6 Sequence number, ones 0 to 9

Deciphering the serial number

The first digit signifies the year the watch was made. It doesn’t tell you the decade – only the year. This will present a problem because you may not be able to distinguish whether the watch was made in 1997 or 2007. The digits always range from 0 to 9.

The second digit denotes the production month. Seiko uses 1-9 for January to September. October is represented by the number 0 (zero, not the letter "O") while November and December are abbreviated to "N" and "D" respectively.

The remaining 4 digits represent the production number of the watch in a sequence. It is generally believed that the first watch produced every month begins with "0000" and the last watch made in that month ends with "9999". Going by this convention, up to 10,000 watches of a particular model could be manufactured in one month. The sequence number is reset for the following month. Therefore if Seiko made up to 4,900 pieces in February, the last watch produced will have the the sequence number 4900. For the following month of March, the first watch produced will have the sequence number 0000 instead of 4901.

The following table below gives examples on how the serial numbers are interpreted:

Caliber Serial Number Year Month Watch Number 7S26A 717872 1997 January 7872 7T32 8N1030 1998 November 1030 6105 200421 1972 October 421 6138 731999 1977 March 1999 6309 4D8001 1984 December 8001 8L35 259393 2002 May 9393 7S26B 760023 2007 June 23

Jayhawk’s Production Date Calculator

Fortunately there is an automated method of determining when your Seiko was made. Savvy Seiko watch enthusiasts have been using Jayhawk’s Production Date Calculator to check when their watches were made. It’s linked from the Seiko & Citizen Forum and to my best knowledge, it is currently the only automated tool for dating your Seiko watch on the Internet.

It’s easy to use – just enter your movement number and the serial number and hit the Calculate button. There you have it – your watch’s date returned to you in a matter of seconds! 🙂

However, there are a few caveats that you need to know when using the Production Date Calculator:

Firstly, the results that are returned to you are based on the accuracy of the internal database table. There may be unintended mistakes in the range of the years entered into the table.

The calculator does not take into account for calibers that are made for more than 10 years.

The production date calculator does not cover the entire list of Seiko calibers made.

The problem lies in Seiko’s numbering convention as it used only one digit to represent the year. The first digit only signifies the year number in a certain decade (10 years). While it is true that Seiko movements are discontinued in less than a decade, there are however, some exceptions to the norm.

A well known example is its very popular 7s26 automatic caliber. If you enter a serial number beginning with "7" or "8" for a post-2000 made 7s26, the date calculator will return you the years 1997 or 1998 respectively, which is off by a whopping 10 years! Even if you are certain that your watch was made in 2006, the date calculator will still think that it was made in 1996.

Here’s why:

The Production Date Calculator unfortunately doesn’t have the ability to account for calibers that have been made for a decade or longer. It merely checks the first digit in the serial number (the year of production) and compares it with its internal table of calibers with the starting year. Since Seiko uses only one digit to denote the production year, the calculator cannot determine the exact decade the watch was manufactured.

For instance, 7s26a caliber was first introduced in 1996 and therefore it naturally assumes that it was from the 1990s. The replacement 7s26b caliber however, came out in late 2006 but the production calculator does not take this into consideration.

Caseback dating dilemma: Was this Seiko 5 Superior from January 1997 or January 2007? It’s actually from 1997.

Manually dating a Seiko watch

Fortunately, there is an alternative to the Production Date Calculator if it returns you erroneous or dubious results. In order to do this, you will have to date the watch by manual means that can give you an approximation or the exact the decade the watch was made.

If you’re interested in pursuing this topic, learn how to manually date a Seiko watch here.

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