Deciphering SEIKO Part Numbers

SEIKO Model, Case and Part Number Codes

How to read and interpret SEIKO codes, including some common Part Numbers as well as Model and Serial Numbers.

This article includes tools to help decode common part numbers to help find generic replacements, interpret model and serial numbers to determine caliber and date of manufacture, and a transcript of SEIKO's manual on case and gasket coding for reference.

Table of Contents


Part Number Decoders
SEIKO Coding Document Transcribed
World Time Watch Part Numbers

Gasket Part Number Decoder

Enter your gasket code here to decode the size, shape and other qualities. This will help you find a matching after-market gasket equivalent.

Cross Section Width Size Color tone Shape Serial No
Part Number Scheme
Width
Thickness
Size
Inner Dimension
Color
Shape
Cross Section
Material
Serial No
Where to find a Gasket Part Number

Use the Model Number Decoder (click here) for parts listings on either Jules Borel or Boley. Locate the part number for the gasket in question and enter it in the decoder above. Be sure to find the original part number. Replacement part numbers are typically also listed, but these do not follow SEIKO's part number scheme and cannot be decoded here.

Crystal Part Number Decoder

Enter your crystal part number here to decode the size, shape and other qualities. This will help you find a matching after-market crystal equivalent. Be sure to set the Part Number Scheme option to reflect the manufacture year of your watch, either before 1990 or from 1990 onward.

Size (Diameter) Type Serial No Material Finish Color Tone Shape / Sub
Size
Diameter
Type
Serial No
Material
Finish
Color Tone
Shape / Sub
Where to find a Crystal Part Number

Use the Model Number Decoder (click here) for parts listings on either Jules Borel or Boley. Locate the part number for the crystal in question and enter it in the decoder above. Be sure to find the original part number. Replacement part numbers are typically also listed, but these do not follow SEIKO's part number scheme and cannot be decoded here.

Model Number Decoder

And Part Number Finder

The model number is found on the case back and should be an 8-digit sequence of numbers and/or letters, in two segments. Here are some valid model numbers: 6217-7000, A239-502A, M158-5009, etc.

Movement Code Case Code Region
Movement Caliber
Case Code
Region Code
Jules Borel Parts List
Boley Parts List
Where to find the Model Number

The model number is located on the case back, noted in two 4-digit segments. Here are some examples.

Model No. A708-5000, 1984 - 1988
Model No. M158-5000, 1977 - 1979
Model No. 6117-6400, 1969 - 1976
Model No. 6217-7010, 1966 - 1967

Serial Number Decoder


The serial number is found on the case back and should be an 6-digit or 7-digit sequence of numbers and/or letters.

Year of Production Month of Production Production Sequence Number
Production Year
Production Month
Production Number
Where to find the Serial Number

The serial numbers is located on the case back, as a series of numbers with either 6 or 7 digits. All digits will be numeric, except perhaps the second digit, which may be numeric or also an N or D. Here are some examples.

Serial No. 730076: March 1977, Production No. 0076
Serial No. 752635: May 1977, Production No. 2635
Serial No. 0N2781: November 1970, Production No. 2781
Serial No. 752635: December 1967, Production No. 8196

Crown Part Number Decoder


Older Seiko Crown Part Numbers were 8 alpha numeric digits, newer codes are 10-digits. Select which type of code you are entering (8 or 10 digits) and paste or type the code to decode the crown part number's properties.

Size Type Serial Number Finish Color tone Assortment
Size
Screw Diameter
Type
Serial No
Material
Finish
Color tone
Assortment
Sub
Where to find a Crown Part Number

Use the Model Number Decoder (click here) for parts listings on either Jules Borel or Boley. Locate the part number for the crown in question and enter it in the decoder above. Be sure to find the original part number. Replacement part numbers are typically also listed, but these do not follow SEIKO's part number scheme and cannot be decoded here.

SEIKO Coding Document Transcribed


First, here are the source documents:

Click the image to download the PDF of the SEIKO Crystal Coding pages scan
Click the image to download the SEIKO Gasket Coding pages scan as a PDF.
Click the image to download the SEIKO Crown Coding pages scan as a PDF.

The following text has been modernized, reformatted and re-purposed from the document scans above. Most of the wording is lifted from the originals, updated and corrected as errors are found.

Crystal Part Number Coding


The structure of the parts number for the glass is classified into two groups according to the shape of the glass, that is, whether the glass shape is round or not.

Round Glass (10 digits)

Round glass / crystals are codes in the following segments:

Code Segments

NOTE: In the coding system for glass, type code and finish code have been revised from 1990 for new models. The following examples show the pre-1990 and post-1990 coding changes.

Example Code, before 1990
Example Code, after 1990
Size Code

The Size Code shows the glass diameter in three numerical digitals. For Example:

Outer diameter of crystal
Type Code

The Type Code is expressed in one letter.
-OLD-

No accessory With tension ring With ring or bezel With other accessory
Water Resistant W T V, G X
Non-water Resistant N D R Y

-REVISED-
The following two letters are newly used to identify the mounting structure of the glass. "N" and "W", which were used so far to denote the water resistant quality, have been replaced by the new classification.

  • A: Bonded
  • P: Pressed in using plastic gasket

For Example

Old New
200N21SN01 200A01SN01
RE0W15JN02 RE0P01JN02

NOTE: "N" and "W" will still be used for glasses having other types of mounting structure such as welded glass.

Serial No. Code

A number from 01 to 99 is assigned for the purpose of production-related classification.

Material Code

Expressed in one letter, as follows:

  • A: Acrylic glass
  • E: Acrylic glass/others
  • G: Hardlex glass (Inorganic tempered glass)
  • H: Hardlex glass (Inorganic tempered glass)
  • J: Hardlex glass (Inorganic tempered glass)
  • K: Hardlex glass (Inorganic tempered glass)
  • L: Hardlex glass (Inorganic tempered glass)
  • S: Sapphire glass
  • Z: Others
Finish Code

Expressed in one letter, as follows:

No-treatment Treated
Printed Evaporated
Classifications Old Revised Old Revised Old Revised
Ordinary finish N M * V *
Cut C N H * J *
Curved K N U * R *
No reflection coating B * G * W *
Antistatic coating D * P * T *
Ion plating treatment, etc. E * Z * L *
Anti-fogging coating A F Y

NOTE:

  1. * .......... A numeral (from 1 to 9) or a letter of the alphabet (M, V, H, J, R and S) is assigned in the order in which the code is established.
  2. Curved glass (K) and cut glass (C) are newly classified as ordinary glass (N).
Color Tone Code

Expressed in one letter, as follows:

  • M: Green
  • L: Blue
  • P: Pink
  • V: Violet
  • Y: Yellow
  • O: Transparent
  • S: Transparent w/ silver color ring
  • G: Transparent w/ gold colored ring
  • E: Others
Shape Code

One letter to show the cross section of the glass.
There are a great variety of cross sections, and the following are typical examples.

A type
B type
C type
Sub Code

One numerical digit to show the slight difference in color tone.

Shaped other than round glass (10 digits)

The first three digits have a different meaning from those for the round shaped glass.

Code Segments

NOTE: In the coding system for glass, type code and finish code have been revised from 1990 for new models. The following examples show the pre-1990 and post-1990 coding changes.

Example Code, before 1990
Example Code, after 1990
Shape Codes

Expressed in two letters to show the plane view of glass.
The following gives typical shapes.

Shape Code Description
AL Almond
TD Teardrop
SQ Square
RE Rectangle
BA Barrel
KO Oval
SA
WA Lozenge
N/A ES Other
Serial No. Code

A number from 0 to 9 is assigned for the purpose of production-related classification.

Gasket Part Number Coding


Gasket codes are classified into three groups as follows:

  1. Non plastic gasket (9 digits)
    1. Previous coding system
      The 3rd and 6th digits are numerical in the previous system.
    2. New coding system
      The 3rd and 5th digits are numerical in the new system
  2. Plastic gaskets (8 digits)
    1. Coding system of "OTHER CASING PARTS" on page 14.
Previous Coding System (9 digits)
Code Segments
Example Code, before 1990
Cross Section Code

One alphabetical digit to show the shape of the cross section

Shape Code Description
A A-shaped
D D-shaped
F Square shaped
B B-Shaped
O O-shaped
N/A E Other
Width Code

One alphabetical letter to show the cross section width.

Thickness Measurement

Example values are:

  • A: 0.60mm
  • B: 0.75mm
  • C: 0.90mm
  • D: 1.05mm
  • E: 0.85mm
  • F: 1.30mm
  • G: 0.40mm
  • H: 0.50mm
  • I: 0.55mm
  • J: 0.80mm
Size Code

Four numerical digits to show the inside diameter of the gasket between 9 o'clock and 3 o'clock sides.

Inner Dimension measurement

Example values are:

  • 2980: 29.8mm
  • 2920: 29.2mm
  • Etc.
Color Tone Code

One alphabetical letter to show the color of the gasket, as follows:

  • B: Black
  • L: Blue
  • N: Grey
  • O: Transparent
  • W: White
  • Y: Yellow
  • E: Others
Shape Code

One numerical digit to show the plan view of the gasket. If a parts number is given 7-digits, the shape code is omitted.

Shape Code Description
0 Circle
1 Square
2 Rectangle
N/A 3-9 Other Shapes
Serial No Code

A number from 1 to 9 assigned to differentiate the shapes and materials. In cases with 7-digit notation, the serial no code is omitted.

New Coding System (9 digits)
Code Segments
Example Code, after 1990

The new coding system retains the previous codes for the following:

  • Cross Section Code
  • Color Tone Code
  • Serial No Code
Width Code

Example width code values for the new coding system are as follows:

  • A: Less than 0.19mm
  • B: 0.20 - 0.29mm
  • C: 0.30 - 0.39mm
  • D: 0.40 - 0.49mm
  • E: 0.50 - 0.59mm
  • F: 0.60 - 0.69mm
  • G: 0.70 - 0.79mm
  • H: 0.80 - 0.89mm
  • J: 0.90 - 0.99mm
  • K: 1.00 - 1.09mm
  • L: 1.10 - 1.19mm
  • M: 1.20 - 1.29mm
  • N: 1.30 - 1.39mm
  • P: 1.40 - 1.49mm
  • R: 1.50 - 1.59mm
  • S: 1.60 - 1.69mm
  • Z: More than 1.70mm
Size Code

Example size code values for the new coding system are as follows:

  • 298: 29.8mm
  • 012: 1.2mm
  • 007: 0.75mm
Shape Code

Example shape code values for the new coding system are as follows:

  • A: Circle
  • B: Square
  • C: Rectangle
  • D: Gable (generally triangular)
  • Z: Others
Material Code

Material codes are missing the scanned source documents and images. If you have a copy of this missing information, please reach out!

Crown Part Number Codes


There are old (8 digit) and new (10 digit) coding systems.

Old 8-Digit Codes
Old Coding System Layout
Example Code Old 8-Digit Layout
Size code

Two numerical digits to show the outside diameter of the crown.

Example value: 35 = 3.5mm
Type Code

One letter to designate the crown function

Water resistant crown M-Type
Gasket is provided outside
W-Type
Gasket is provided inside
E-Type
with stem
Non-water resistant crown N-Type
Ordinary design
D-Type
with dust-proof pipe
S-Type
with dist-proof spring washer
R-Type
with gasket
E-Type
Others: Stopwatch, etc.
Serial No code

A number from 01 to 99 is assigned to differentiate the appearance.

Finish code

Expressed in one letter to desgnate the surface finish of the crown.

  • N : Ordinary finiah
  • D : Diamond-cut finish
  • E : Others
Color tone code

One letter to show the material and the kind of surface plating.

A, B, D, F, N SGP (Gold tone)
C CRP (Chromium plating)
E 18K (18-carat yellow gold)
X 18K (18-carat white gold)
J PDP (Palladium plating)
M 14KWG (14-carat white gold)
S Stainless steel
Z 14K (14-carat yellow gold)
Assortment code

One numerical digit or letter to show the type of marking on the crown.

1 without mark
2-3 with mark
4-9 Others
A-E with jewel
New 10-Digit Codes
New Coding System Layout
Example Code New 10-Digit Layout
Screw diameter code

A numeral to identify the type of screw that fits the winding stem.

  • 1 : No screw
  • 6 : 60P15
  • 8 : 80P20
  • 9 : 90P22.5
Screw diameter schematic
Type code

A letter excluding I, O, Q and U to classify the type of crown.

A-Type
Dust-proof (without gasket)
E-Type
Screw lock type with winding stem (High-pressure water resistant)
K-Type
With a fixing ring (High-pressure water resistant)
M-Type
Gasket makes contact with the inside of the winding stem pipe (Water resistant, Non-water resistant)
E-Type
Others: Stopwatch, etc.
Size code

The first two figures of the outside diameter of a crown.

Example value: Outside diameter 325 (3.25mm) = Size code 32
Serial No. code

Consisting of two digits; a letter excluding I, O, Q and U for the first digit and a numeral for the second digit.

Material code

A letter excluding I, O, Q and U to denote the material of the crown head.

  • B : Brass
  • K : 18K (* Color of gold is classified by the color tone code.)
  • M : 14K (* Color of gold is classified by the color tone code.)
  • N : Ns (Nickel silver)
  • P : Plastic
  • S : Stainless steel
  • T : Titan
  • Z : Others
Finish code

A letter excluding I, O,Q and U to denote the finish of the roulette and head of the crown.

Color tone code

A letter excluding I, O,Q and U to denote the color tone of the crown head.

Sub code

Consisting of a numeral and a letter excluding I, O, Q and U that denote the difference in color tone, material and color tone of jewel and marking. The numeral is assigned in the order in which the code is established.

World Time Part Numbers


The following parts charts are focused on consumable parts, like gaskets and crystals. Click on the model no in the first column to open a new tab to the Jules Borel database, which contains additional part numbers.

Generation 1: Mechanical Watches
Model No Crystal / Glass Caseback Gasket
6217-7000 341W02AN 0C3060B0A
6217-7010 350W02AN 0C3280B01
6117-6010
6117-6019
340T06ANS0 or 340T06AN FH2920B01
6117-6400
6117-6409
350T02ANS or 350T02ANG FH2980B01
Generation 2: Digital Watches
Model No Battery Crystal / Glass Crystal Gasket Caseback Gasket Battery Hatch Gasket Pusher Gasket Pusher Retaining Clips
M158-5000
M158-5009
SR1130W BA0W66GN00 8617.9900 (black)
8617.9901 (brown)
FZ2960B0 EH1175B01 DJ0060B01 TBD
A358-5000
A358-5009
SR1120W SA1W24GN00 86178920 0Z2701B01 N/A 0A0064B01 TBD
A239-5000
A239-5009
A239-5010
A239-5020
A239-502A
SR927W ES0W81HN00 86171300 0B2910B04 011140B0A TBD TBD
A708-5000
A708-5010
CR2016 SA7W06GN00 86571820 TBD N/A EG0060B01 83200271
A718-5010 CR2016 ES6W18GN00 86571460 FH2980B01 or FH2980B0A N/A EC0060B0A 83200271
A718-5030 CR2016 SA3W92GN00 86571380 TBD N/A EG0060B01 83200271
Ad from Google

Related Articles


Old Ad Scans: Seiko World Time 6117-601X

A small collection of ad and catalog scans of the SEIKO World Time 6117-601X

The Seiko World Time 6117-601X

All about the 3rd series world time watch from SEIKO, produced from 1968 through 1969

Old Ad Scans: Seiko World Time 6117-640X

A small collection of ad and catalog scans of the SEIKO World Time 6117-640X

The Seiko World Time 6117-6409 in Gold

All about the gold/gilt world time watch from SEIKO, produced in 1972

Authenticating The Seiko World Time 6117-640X

Tips on confirming the originality of your Seiko World Time 6117-640X

The Seiko World Time 6117-640X

All about the 4th series world time watch from SEIKO, produced from 1969 through 1976

The Seiko World Time 6217-7000 - 1967

All about the reproduction of the first series world time watch from SEIKO in 1967

The Seiko World Time 6217-7000 - The Dolphin

All about the Dolphin World Time watch from SEIKO, December 1964

Authenticating The Seiko World Time 6217-7000

Tips on confirming the originality of your Seiko World Time 6217-7000

The Seiko World Time 6217-7000

All about the first series world time watch from SEIKO in 1964

The Seiko World Time 6217-7010 - Asian Games

All about the Asian Games World Time watch from SEIKO, August 1966

The Seiko World Time 6217-7010 - Standard Edition

All about the 2nd Series World Time watch from SEIKO in 1967

Old Ad Scans: Seiko World Time 6217-7000

A small collection of ad and catalog scans of the SEIKO World Time 6217-7000

Counterfeits and Copies of The Seiko A239

As the saying goes, imitation is the highest form of flattery. And the SEIKO A239 had quite a few admirers.

The Seiko World Time A239-50XX - The WOPR

All about the 3rd series of digital LCD world time watch from SEIKO, produced in 1979

Old Ad Scans: Seiko World Time A239-50XX

A small collection of ad and catalog scans of the SEIKO World Time A239-50XX

The Seiko World Time A358-500X - The Alarm

All about the 2nd series of digital LCD world time watch from SEIKO, produced in 1979

The Seiko World Time A708-5000 - The TWA

All about the 4th series of digital LCD world time watch from SEIKO, produced from 1984 through 1988

The Seiko World Time A718-5010 - The Frankenstein

All about the A718-5010 digital LCD world time watch from SEIKO, produced in 1984

The Seiko World Time A718-5030 - The John Cleese

All about the A718-5030 digital LCD world time watch from SEIKO, produced in 1984

Reference Cities - Changes over the Years

A history of changes to the Cities Dial Frames on SEIKO World Time digital watches from 1977 through 1988

Reference Cities - Changes over the Years

A history of changes to the Cities Bezel on SEIKO World Time mechanical watches from 1964 through 1976

The Date Wheel - Changes over the Years

A history of changes to the Date Wheels on SEIKO World Time mechanical watches from 1964 through 1976

The Dial - Changes over the Years

A history of changes to the Dials on SEIKO World Time mechanical watches from 1964 through 1976

Counterfeits and Copies of The Seiko M158 PAN AM

As the saying goes, imitation is the highest form of flattery. And the SEIKO M158 had quite a few admirers.

The Seiko World Time M158-500X - PAN AM

All about the 1st series of digital LCD world time watch from SEIKO, produced in 1977

Old Ad Scans: Seiko World Time M158-500X

A small collection of ad and catalog scans of the SEIKO World Time M158-500X

Authenticating The Seiko World Time M158-500X

Tips on confirming the originality of your Seiko World Time M158-5000 and M158-5009

Ad from Google
Link Copied
The link has been copied to your clipboard!