1. Seiko Watch Serial Number Lookup
2. Seiko Watch Serial Number History
3. Seiko Quartz Watch Serial Numbers
4. Seiko Watch Model Numbers Meaning

The 1960s saw many in the watch industry looking to capitalise on increased demand for automatic watches. In 1969, Seiko delivered by introducing what was arguably the world’s first automatic chronograph, the Seiko 6139. This article focuses on its earliest incarnations, the 6139-600X. A watch often called the “Speed-Timer”. Seiko printed the term “Speed-Timer” on many of its early chronographs destined for the Japanese market, indicating the more advanced features, such as a thirty-minute chronograph recorder, a day and date indicator, and a tachymeter scale. Production of the Seiko 6139 line up ended sometime in 1978, but are still readily available today. The 6139-600X series is quickly becoming very collectable pieces thanks to a combination of great design and storied history. The 600X has two big claims to fame, as both a contender for the world’s first automatic chronograph and as the first chronograph worn in space.

Seiko Men’s Watches. Shop Manufacturer Direct, Free 2-Day shipping on all orders. Two Year Manufacturer Warranty. Seiko fine Japanese automatic, chronograph, diver, quartz Men’s wrist watches. Website featuring Seiko USA Watches for direct purchase from Seiko. Seiko 5 Sports, Prospex, Presage, Essentials, wrist watches. Seiko watches use a 6 or 7 digit serial number stamped on the caseback. This serial number contains digits indicating the date. The first digit translates to the year and the second shows the month. As only 1 digit is used for the year this will only show you the last digit of the year, the decade cannot be found from the serial number, more on this later. To start let us look at a typical model number: Seiko 5 model SNKL23J1. The first part of the model SNKL23 is the specific watch model number first indicating the collection SNKL and then the model within that collection 23. The J means that at least 51% of the watch was manufactured/assembled within Japan proper as per Japanese government stipulations. Please note that additional Seiko resources can be found on the wonderful site www.plus9time.com, which is run by the dedicated Seiko expert, Anthony Kabel. He has many great articles and reference materials about Seiko watches on that site. Many, if not all of the vintage catalogs that I collected likely came from Anthony’s collection.

Seiko Watch Serial Number Lookup

THE WORLD’S FIRST AUTOMATIC CHRONOGRAPH

There is still debate in terms of which watch holds claim to the title of world’s first automatic chronograph, but really, it all boils down to which type of “first” you would consider most appropriate. Back in 1969, several big names were competing for the title of the world’s first automatic chronograph. The first watch company to lay claim to the title was Zenith, who introduced their first prototypes on January 10, 1969. The company even named their automatic chronograph the “El Primero” or “The First” in Spanish. The second contender was a collective of watchmakers, which could be termed the Chronomatic group, namely Heuer, Breitling, and Hamilton-Buren. The companies created a mutually beneficial partnership and worked together in developing their automatic chronograph. The group laid claim to the title by introducing the Chronomatic prototypes on March 3, 1969, in a much-highlighted press event. The Chronomatic group was also the first to show several models of pre-production samples during the Basel Fair in April of 1969, a more impressive showing when compared to Zenith, who had fewer samples during the same event. Last but not least, Seiko lays claim to the title by being the first to start serial production of their 6139 “Speed Timer” in May 1969. These early watches were to be released to the Japanese market only. On the other hand, the Chronomatic group started production and release to the world’s retail markets in June or July of 1969, and Zenith’s chronograph was released into the wider world market in October 1969. Some serial numbers of the earliest Seiko 6139s indicate a production date of March 1969 or even as early as February 1969, but it is unclear if these are samples or were the first ones intended for the Japanese market.

To sum it up, Zenith may have been the first to announce the development of the first automatic chronograph, but Heuer, Breitling, and Hamilton-Buren were the first to release their automatic chronograph to major retail markets. However, when it comes to who first achieved serial production of the automatic chronograph, Seiko may have quietly beaten both, by releasing to the Japanese market in May 1969.

From left to right: Zenith ad from 1969; Heuer vintage ad; Seiko 1969 catalog

THE FIRST CHRONOGRAPH IN SPACE

Col. Pogue wearing his Pogue Seiko
Image by Heritage Auctions

Aside from being the first automatic chronograph to achieve serial production, the Seiko 6139 was also the first automatic chronograph in space. This honor used to be bestowed upon Sinn 140 worn by a German astronaut named Reinhard Furrer during the Spacelab D1 mission in 1985. It was only in 2007 that it was established that Col. Pogue wore a 6139-6002 during the NASA Skylab 4 mission which took place in 1973. The official watch to be used for the Skylab 4 Mission was the Omega Speedmaster Professional, but it was only issued shortly before the actual launch. Needing a watch to use during his pre-flight training, Col. Pogue bought a 6139-6002 from PX at Ellington AFB Exchange. He utilized it to time engine burns during the course of his training, which lasted for more than six months. Due to his familiarity with the 6002, Col. Pogue launched into space on Nov. 16, 1973, with the piece tucked in his suit leg pocket. For the length of the mission, he wore it on his left arm alongside the NASA certified Omega Speedmaster on his other arm. As Col. Pogue had been using the 6002 during the course of his training and found it very handy, he did not attempt to get official approval from NASA to carry it with him into space. The astronaut, however, stated that he did not wear the piece during the EVA Spacewalk. The 6002 came back with Col. Pogue on February 8, 1974, when the mission ended. Since this fact was discovered, the yellow dial with the yellow indicator ring variation of the 6002 has been commonly termed as a “Pogue”.

THE BEZELS

Aside from being the first automatic chronograph in space, the 6139-600X series also has another popular identifying factor, it’s outer bezel. Because of its red and blue color, the fixed outer bezel has been commonly referred to as the “Pepsi” bezel. The “Pepsi” bezel displays the tachymeter scale and has remained a consistent feature throughout the years of production of the 600X series.. The 600X also has a rotating indicator ring, or what is sometimes called an inner bezel. It is made of plastic with markings for 60 minutes. The most common colors can be seen in the Seiko catalog scan below. These are the blue indicator rings for the blue dials and yellow indicator rings for the yellow dials. Two other variations pop up from time to time. They are the white and black indicator rings.

1969 Seiko Catalog

In some instances, pieces can be found with white indicator rings; however, it is likely that these are simply yellow indicator rings that have discolored over time due to UV exposure. There is little evidence these white indicator rings are a genuine release and should probably be avoided. There is also a far less common black indicator ring, which can be usually found with a silver dial. There are some who doubt the authenticity of the black indicator ring, but enough evidence is present to suggest these were an official release.

A 6139-6000 silver dial 1969 and a 6139-6002 with yellow dial and black indicator ring
Left image by LINCE via RPTcom; Right image by hal0eight via Wrist Sushi and Vintage Time Australia

THE DIALS

There are three different colours for the dials, yellow, blue, and silver with three variations for each colour. The markings on the dial, or lack thereof, depend on the year of its release. Since the series’ introduction, the label on the dial by the 12 o’clock mark has always been “Chronograph Automatic” or just “Automatic”, for non-JDM(Japanese domestic market) models. As for the words on the 9 o’clock mark, it reads “Water 70M Proof” from its release until the earlier part of 1970. These are commonly referred to as “proof models” or “proof dials” and tend to be more desirable to collectors.

After this time, the markings changed to “Water 70M Resist”. This shift was due to a law passed in 1968 that required manufacturers to change the markings on the watches they produce to water-resistant. The change across all manufacturers was not instantaneous. Seiko started employing this from 1970 and finished changing the markings on most of their models by 1971. Sometime during the latter part of 1972, the company also removed the marking stating “Water 70M Resist” but retained the marking “Water Resistant” on the case back.

From left to right: “Proof” dial, “Resist” dial, and dial with no markings

The silver dialed variation is by far the rarest dial and is even more seldomly seen with a “proof” variation. There are only a few instances of photographed silver “proof” dials.

A silver “Proof”dial from 1969 and a silver “Resist” dial from 1971
Left image by LINCE via RPTcom

All in all, there are three dial colors with three variations, the “proof”, “resist”, and those with no markings, amounting to nine verified dial combinations.

Nine dial variations for the Seiko 613-600X throughout its production

JDM DIAL VARIATIONS

In addition to the standard models listed above, watches that were intended for the Japanese Domestic Market (JDM) only had a few additional markings. The markings on the dial would say “Speed-Timer” at the 12 o’clock mark, and “5 Sports Water 70 Proof” at the 9 o’clock mark for those produced between 1969 and 1975. After this period, the JDM dials produced would bear the markings “5 Sports” on the 12 o’clock mark and “Speed-Timer” on the 9 o’clock mark.

Early JDM 6139-6000 dial and New JDM 6139-600X dial

THE CASE

The 6139-600X series comes in a stainless steel Screwback case with square corners that measures 40mm in diameter. The case back houses the model number and serial number for the piece. If you would like to determine the date of production, you only need to check the first two digits of the serial number which tells you the year and month of production respectively. (Quartzimodo’s Time Journal has a very helpful article about determining the date of production of a Seiko watch.)

The case back also features the markings “Waterproof” and “Water Resistant”, which is also a good indicator of its date of production. Those that contain the markings “Waterproof” were produced from 1969 to February of 1970. The pieces produced after this time would contain the markings “Water Resist” or “Water Resistant” due to Seiko complying with the mandate that watches manufacturers change their markings to reflect water resistant. It is estimated that the “Water Resist” case backs were used until April or May of 1970 before the company shifted to using “Water Resistant” markings on their case backs.

Left to right: “Waterproof” from ‘69, “Water Resistant” from ‘72, and a later version of the “Water Resistant” from ‘77.

Another variation that the case for the series went through is the notch on the side by the crown. The notched case was used for the series from 1969 to, it seems, the latter part of 1970 or early 1971. From then on until the end of its production, 6139s have featured the non-notched case. This is the reason why notched cases tend to be more desirable to most collectors.

Notched 6139-6000 from April 1969 and non-notched 6139-6005 from 1978

It is hard to pinpoint the exact date when the company transitioned to using the non-notched case as during the year of 1970, there were some pieces that had a notched case but featured the markings “Water Resist” on its case back.

Ad from 1970 (left photo), Water Resist notched case from March 1970 (middle and right photo)
Middle and right image by SeikoPsycho2 via SCWF

The working theory is that the company used the leftover notched cases from the time they stopped producing until finally running out in late 1970 or early 1971. A notched case “Waterproof” model from April 1970 also indicates that the left over case backs were also utilised.

THE 6139 BRACELET

There are four known variations for the bracelets of the 6139-600X series. The first one being the H-link bracelet with straight ends, which was used on the 6139-600X series from its introduction until 1973. After this period, the H-link bracelet with tapered ends was used until the end of production. Another variation is what is commonly termed as the Stelux bracelet. It is unsure when this particular type was used, but is usually seen combined with the silver dial. The last variation is those seen for the versions intended for the Japanese market, or what is commonly referred to as “JDM bracelets”. This variation was used for the JDM models all throughout its production.

Straight H-link; Tapered H-link; Stelux bracelet; JDM bracelet

THE MOVEMENT

There were two types of movement used for the 6139s and are not specific to the 6139-600X series. The first one is the 6139A, which was used from 1969 to sometime in 1970 to 1971.he second one is the 6139B, which replaced the 6139A and was used until the end of production. Most of the differences can be found on the parts used for the 6139B series, such as the center chronograph wheel, which was made to be more robust. The “B” movement was also said to have a simplified chronograph bridge.

There are 2 versions for each of the movements, 21J and 17J, signifying the number of jewels used for each one. The 21J movements can be only be found in the JDM version of the series, and the 17J movements can be found in the non-JDM versions.

The series has had several incarnations and variations throughout its years of production.

THE EXECUTIONS

There are six possible references for the 600X series. These are: 6139-6000, 6139-6001, 6139-6002, 6139-6005, 6139-6007, and the 6139-6009. The differences in the last digit of the model numbers only signify its intended region of release. The 6139-6000 seem to correspond to those intended for the Japanese market. The 6139-6005 and 6139-6009 are those intended for North America.

All in all, with the six possible references, 15 possible dial variations for both JDM and non-JDM versions, 3 colors of inner rings, 2 cases, 3 case backs, 2 types of movements, and 4 possible bracelets, there is a huge array of possible combinations. However, bear in mind that only the JDM versions have the “Speed-Timer” dial, 21J movements, and the fourth type of bracelet, or what is commonly known as the “JDM bracelet”.

For the 6139-600X series, there could well over be 70 variations for the non-JDM versions and 18 for the JDM versions. Unfortunately, this figure cannot be ascertained as it is yet unclear which incarnations were available for each region the series was released.

RECOMMENDED SEIKO 6139-600X

When trying to acquire a 6139-600X, it is typically best to look for models in as good a condition as possible. Good examples will hopefully require little or no restoration. It is best to always look for the signs of early productions, such as notched cases, the 6139A movement, and “Proof” or “Resist” markings. When looking at a piece, especially ones being sold online, it’s best to always look for pictures bearing the serial number to determine the year of production.

To help you get started, here are some popular variations of the series that you may want to ruminate on:

THE PLACE TO START

When looking for a 6139-600X, try to look for one with a “proof” dial and a notched case. These are sure signs of early production and are more desirable for collectors. However, since these features are only available on early models, it is harder to find pieces that are in good condition. A great place to look is Ebay.com and sales corners on watch forum websites.

A Seiko 6139-6000 with “proof” dial and notched case from April 1969

Prices for those with notched cases and “proof” dials start at around $200 but vary greatly depending on its condition. Pieces that are in near mint condition can be had for $350 and up.

Tip: Try to also look for poorly advertised Seikos. Some posts are not very descriptive or may not even contain a model number as those who sell them may not be familiar with the series. The best clue would be the posted pictures. Like they say, patience is a virtue.

SOMETHING DIFFERENT

Another variation that is sought after is the elusive silver-dialed 6139-600X. This particular incarnation is only usually found with a “Resist” dial or a dial with no markings. These silver dialed versions can also be found online and priced around $350.

6139-6002 silver dial with “resist” markings

THE HIGH END

One of the rarest 6139-600X pieces that can be found are the early JDM or “Speed-Timer” models with the markings “5 Sports Water 70 Proof” on the dial by the 9 o’clock mark. These are very desirable pieces for collectors since these are the first ones produced by Seiko intended for the Japanese market. The early JDM versions are also very hard to acquire, and some are said to have serial numbers that indicate a production date of February or March 1969. Prices for this version start at $320 but can go up to $550, or maybe even more, depending on its condition.

6139-6000 Early JDM from 1969

THE GRAIL

Everyone has their own grail, but for us, it would be a mint example of the 6139-6002 worn by Col. Pogue during the NASA Mission, the first automatic chronograph in space. Col. Pogue bought the piece for $71 on June 13, 1972, and was auctioned off in 2008 for $5,975. The proceeds from the auction went to the Astronaut Scholarship Foundation.

6139-6002 worn by William Pogue during NASA Skylab 4 mission
Image by Heritage Auctions

Good examples of this watch are still readily available. As a collector you can can still find your own “Pogue” 6139-6002 without much trouble. A yellow dialled non-notched 6002 can still be bought today, some even in mint condition, but can fetch quite a price as it is very in demand.

Prices range from $450 up to $1000 for those in near mint. Nice examples but with small defects, such as discoloured rings and replaced bands, can be had for significantly less.

WHAT TO LOOK FOR AND WHAT TO AVOID?

When looking for a 6139-600X, remember that the series are decades old, and as such there are plenty of pieces out there that are franken or may have been modified. In the section below, we will outline common issues or aspects to look at when purchasing your own 6139-600X:

Dial and Bezels: Check for any sign of corrosion, modifications, and replacement parts.

*Remember that there are only a number of known combinations for the dials and indicator rings. Other colors may just be products of restorations or might be aftermarket parts. Specifically, watch out for pieces that have the white indicator ring as this is a sign that it is heavily faded or might have been repainted.

Aftermarket white indicator ring

*The outer bezel only comes in blue and red for these series and is fixed. There are sticker versions of the outer bezel available, so watch out for these when looking for a 600X to purchase.

*Watch out for any corrosion on the dial, especially on the sub-dial of the piece, as this is where it usually starts.

Seiko Watch Serial Number History

*Be careful of aftermarket dials when purchasing your piece. Some signs to watch out for are the marks on the sub dial register. These should touch the very edge of the sub register ring. Also, the lume on the dial should have a sharp edge and not a rounded one.

Left: Sub-dial marks do not come to the age and lume has rounded edges.
Right: The original dial’s markings/indicators for the sub-dial come to the very edge. The lume also has a sharper edge.

Bracelets: Watch out for any missing links on the bracelet of the 600X that you aim to purchase. Also, remember that these series usually come with the H-link straight/tapered style, the Stelux bracelet, and the JDM bracelet. Be wary of replacement bracelets, especially if you are keen on originality.

Seiko Quartz Watch Serial Numbers

An aftermarket bracelet sold online

Case and Movement: Be on the lookout for corrosion in the case and movement of the 600X you intend to purchase. Also, ensure that the markings, model, and serial number of the case are consistent with the other parts of the piece.

Stem, Crown, and Gaskets: Be wary of aftermarket or reproduction stems as this can cause damage to the movement of the piece. The gaskets (black rubber rings) may also need to be replaced. These can become sticky through time and might also affect the water-resistance of the piece.

Seiko Watch Model Numbers Meaning

A genuine stem and crown for a 6139-600X (Left) and an aftermarket stem and crown with gasket (Right)
Left image by hal0eight via Wrist Sushi and Vintage Time Australia

For more information regarding the variations and buying Seiko 6139s, please also visitHOW TO BUY A SEIKO 6139-600x CHRONOGRAPH – A Collector’s Buying Guide by Ty Maitland, 1970’s Seiko 6139-600X Chronograph Variations Review by SeikoPsycho2 from watchuseek, and The Definitive 6139-600x Buyer’s Guide thread from the Wrist Sushi forum.

From The Spring Bar Store:

References:

1. Jeffrey Stein, “Project 99-The Race to Develop the World’s First Automatic Chronograph”, Online guide article, 2008
2. The Seikoholics Forums users Ninja01 and StartSomething, “JDM Speedtimer 6138/6139 Variant Question“, Forum post, 2012
3. Network54 user Kelly M. Rayburn, “My 6139-6005 on Stelux bracelet. . .”, Forum post, 2009
4. SCWF users SeikoPsycho2, aladin_sane, and haloeight, “Need some 6139 expertise!”, Forum post, 2012
5. Wrist Sushi users seikoholic and hal0eight, “Nothing like some documentation – look for the 6139-6000“, Forum post, 2014
6. Ranfft Watches, “ Seiko 6139A” and “Seiko 6139B”,Auction site,(n.d)
7. SCWF user haloeight, “Re: Pogue inner bezel question”, Forum post, 2011
8. Network54 user Isthmus, “unresolved mystery about 6139 resist dial ?“, Forum post, 2008
9. Evan Yeung, “Revisiting An Icon – The Seiko Speedtimer”, Online magazine article, 2012
10. Reddit user Seikoholic, “[Seiko 6139-6005 “Resist”] – aka “Pogue” – 80+ days in orbit, first automatic chronograph in space, and the reason that I started collecting Seikos“, Reddit post, 2013
11. Felix Scholz, “IN-DEPTH: Your Vintage Seiko Chronograph Buying Guide”, Online magazine article, 2012
12. Watchuseek user SeikoPsycho2, “1970’s Seiko 6139-600X Chronograph Variations Review”, Forum post, 2009
13. Watchuseek user SeikoPsycho2 “6139-60XX How to spot an Aftermarket Dial”, Forum post, 2014
14. Quartzimodo Admin, “How to tell when your Seiko watch was made (Part 1)“, Blog post, 2010
15. Arne Rasmussen, “Seiko 6139 (Skylab 4 in 1973)“, Blog post, 2013
16. Timezone.com user rileyn p “I don’t know how else it can be said…”, Forum post, 2008
17. James Lamdin, “The “Colonel Pogue” Seiko 6139“. DREAMCHRONO, Blog post, 2013
18. Chris Lang “My First Mechanical Chronograph is the World’s First Automatic Chronograph: Seiko 6139“, Blog post, 2014
19. SCWF user Librarian2, “Seiko Calibers Technical/Repair Manuals”, Forum post, 2010
20. Watchuseek user Isthmus. “Difference Between “Water Proof” & “Water Resist”….”, Forum post, 2008
21. Ty Maitland reposted by Watchuseek user Isthmus, “HOW TO BUY A SEIKO 6139-600x CHRONOGRAPH – A Collector’s Buying Guide”, Forum post, 2008
22. SCWF user Isthmus, “SEIKO VINTAGE CATALOGS – 1960s – 1980s”, Forum post, 2011
23. Matt Boston, “Top 10 Technically Important Mechanical Wrist Watches“, Blog post, 2013
24. Blake Buettner, “Just Because: Seiko 6139, The Other First Automatic Chronograph“, Online magazine article, 2011
25. Don, “The Rarest Chronograph Movement of Seiko ca.60s/70s“, Blog post, 2010
26. Watch wiki, “Seiko 6139“, Web encyclopedia, 2014
27. WristSushi user hal0eight, “The Definitive 6139-600x Buyer’s Guide“, Forum post, 2014
28. SCWF user Spencer PK, “Re: History of the 6139 – Photo Database Accurate?“, Forum post, 2012
29. Network54 user Cobrajet25, “According to Seiko at least, there is no difference between these watches.>“, Forum post, 2004
30. SCWF users cobrajet25 and LINCE, “6139-600x silver-dialed models…“, Forum post, 2011
31. Network54 user Cobrajet25, “Yes, it is. The really early ones>”, Forum post, 2005
32. SCWF users martback and SeikoPsycho2, “6139-600X dating and identification clues ?“, Forum post, 2013
33. Network54 user swedefreak and Cobrajet25, “6139-600X variations“, Forum post, 2009
34. SCWF user Spencer PK, “Re: 6139- Movement: 17 vs 21 Jewels”, Forum post, 2013
35. SCWF user Spencer PK, “Re: 6139A vs 6139B parts interchange”, Forum post, 2010
36. SCWF user Spencer PK, “Re: A question for the 6139-600X experts….”, Forum post, 2013
37. Watchuseek user SeikoPsycho2, “Re: Does this Speedtimer look original?”, Forum post, 2011
38. SCWF user cobrajet25, “Re: The gold-dialed 6139-600x with a black indicator ring… any proof, ever?”, Forum post, 2012
39. SCWF user Daver, “Seiko 6139B mainspring“, Forum post, 2014
40. Network 54 user Don, “Right there in the search engine. For example:”, Forum post, 2008
41. SCWF users cobrajet25 and Technoman, “6139 dial variations – relative rarities?“, Forum post, 2010
42. Network54 user Cobrajet25, “Not qute…from what I have seen.>“, Forum post, 2009
43. Network 54 users Cobrajet25 and tyes, “Earliest 6139 found #93509X = Mar 1969”, Forum post, 2008
44. Network54 user Cobrajet25, “Your dial is fine…>>“, Forum post, 2008

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