The Chrono Masters

The Chrono Master is a ‘high-end’ watch that first appeared in Citizen’s line-up in 1967. Although it was not the first of Citizen’s watches to include chronometer grade movements, since it was preceded by the hand wound ‘Chronometer’ (1962), it featured a range of models in both hand-wind and automatic forms, and has probably become Citizen’s most recognised high grade vintage watch, especially since modern versions have also been produced. Although there are other high end lines by Citizen, including the Chronometer and models in the Leopard line-up, the Chrono Master is probably the best known.

The Chrono Master is distinguished by the name itself on the upper part of the dial, an applied stylized eagle emblem at the 6 o’clock position and the same motif in a gold medallion applied to the centre of the case back.

This article summarises the history and development of the Chrono Master, with examples and other material shown for reference. Reference and comparative information on their movements and chronology can be found here:

Citizen also made a Chrono Master version of its electro-mechanical watches, and I have included it in Part 2 of this article, alongside the automatic models.

All Chrono Master case backs are marked ‘Parawater’, other than than the solid gold hand wound model, which has a plain back.

Lug sizes – it appears to me that two lug widths are used, 18mm and 20mm. I indicate which model / case uses which width as far as I can, but add ‘?’ where I am not absolutely sure. I know that my own Chrono Master is 20mm, and it appears to me from catalog images that those models sold with a steel bracelet used this width. Those with leather bands only appear to be 18mm.

A quick note about crowns – I can’t be absolutely definitive about crowns for all the Chrono Masters, since many of my reference pictures are straight ahead and only show the profile of the crown. Although it would normally be expected that all crowns should be signed with the ‘C’ mark (rather than ‘CTZ’), it may be true that on some early examples the crown is unsigned. I have observed this on one or two 1967 examples of the 1870 hand-winding model – for more information, see this post:

Part 1

The Hand-Winding Chrono Master

The 1967 Models: Citizen launched the Chrono Master in automatic and hand-winding forms in 1967. Two hand wound models were produced in the first year, using movements 0920 and 1870 respectively. The obvious outward differences are that the 1870 has a date wheel and higher jewelling – 25 rather than the 22 found in the 0920. 

Their specifications are very similar, and they were part of the ’02’ family of movements indicating that they were developed and highly tuned versions of the humble ‘Homer’ range (first produced in 1962). This is immediately clear from the date version of the Homer which uses movements designated 18xx, with the Chrono Master using the 1870 variant. 

The non-date version of the Homer used the 02xx movement, so the ‘0920’ Chrono Master does not follow that convention – only one other movement was designated ’09’, the 0911 used in the ‘Crystate’ and ‘Crystate’ Deluxe’ also first produced in 1967. However, the case number is ‘4-020171’ indicates that it sits squarely in the 02 family – see the 02 ‘Family Tree’:

Two variants of each model were made, one with ‘CHRONOMETER’ on the dial, suggesting a higher degree of adjustment, and reflected in its price at the time (see below). The Chrono Master case back is notable for its gold stylized eagle medallion.

Both versions run at 18,000 beats per hour, and the movements are both 25.60mm wide, with a depth of 4.00mm. I believe that the movement has ‘second setting’ or ‘hacking’, i.e. the movement is stopped when the crown is pulled out to the time-setting position, to allow accurate synchronisation, as do the automatic versions. Both types were also produced in 18K gold. However, the solid gold variants were not marked as Chrono Masters, but were more simply marked ‘CHRONOMETER’, ‘OFFICIALLY CERTIFIED’ and have a (very) plain case back.

0920 Chrono Master – note there is no jewel count on the dial, lug width 18mm?:

0920 Movement – marked with jewel count and movement serial number (note: this is not the same as the serial number on the case back):

0920 Chrono Master Chronometer, lug width 18mm?:

0920 Case Back (this example is engraved, probably an award to a long serving employee). The case back number is 4-020171, but the earlier style of ‘HOOS3002’ can also be found:

1870 Chrono Master – dials are marked with the jewel count & ‘DATE’, lug width 18mm:

1870 Chrono Master movement – marked with jewel count but no movement serial number:

1870 Case Back – case number is HODS2901 on this example, but can also have the later style of case number ‘4-180194’:

1870 Chrono Master Chronometer, lug width 18mm:

1870 Chrono Master Chronometer movement, with jewel count & movement serial number:

The 18K Solid Gold Models, lug width 18mm?  – no jewel count on either version, :- 


0920 Movement – with jewel count and movement serial number:

1870 Movement:

1870 Movement, with jewel count and movement serial number:

18K Case back:

The 1968 Models: The following year saw the launch of the 0930 movement, extending the range with even more finely tuned movements. Two dial variations are found, one simply marked ‘Special’, achieving chronometer grade, and the other marked ‘SUPERIOR CHRONOMETER’ as well as ‘SPECIAL’, suggesting accuracy better than standard chronometer grade. No additional date models (1870 movement) were launched.

Notably, the 0930 22 jewel movement now featured a fine adjuster on the balance, not found on the earlier two movements. 

0930 Chrono Master Special, lug width 18mm?:  – no jewel count on the dial, as with the 0920, 

0930 Movement – with jewel count & movement serial number, adjuster on the balance:

0930 Chrono Master Superior Chronometer Special, lug width 18mm? – no jewel count, with gold eagle motif (see catalog scan below), :

0930 Chrono Master Superior Chronometer Special movement, as the ‘standard’ Special, with movement serial number and fine adjuster:

0930 Case Back, case number 4-020201 – the earlier style of HOOS2801 can also be found:

I am not certain as to the production run for the hand wound Chrono Master models – a table (in Japanese) that I have suggests they were produced until 1972 based on my own deductions from model listings and their jewel counts. Here are catalog scans from the 1971 catalog of two examples, which also show the types of strap used:



The standard Chrono Master’s accuracy when it was launched in August 1967 was -5 to +10 seconds per day. I have not found performance certificates for any of the Citizen Chrono Masters, but here is one for their 1962 Chronometer model (I would imagine that the same standards would be applied to the Chrono Master chronometers). I believe these correspond closely to the COSC standards at that time:

Original Prices:
These are the prices when the models were first launched – all in Japanese Yen of course:


22j, SS Chrono Master


22j, SS Chrono Master Chronometer


22j, 18K Gold Chronometer.



22j, SS Chrono Master Special


22j, SS Chrono Master Superior Chronometer Special



25j, SS Chrono Master


25j, SS Chrono Master Chronometer


25j, 18K Gold Chronometer


Original Packaging:

0920 Chronometer with Tags:

0930 Superior Chronometer Special with Tags:

Chrono Master Outer Box:

Chrono Master Chronometer Date Box:

Chrono Master Leather Strap – note the leather insert on the buckle:

Part 2

The Automatic Chrono Master, 1967

Citizen launched all bar one of their automatic versions of the Chrono Master in 1967, the same year as their first hand-winding model, and were produced until 1972. The movement is essentially the same for each version, in either 33 or 35 jewel form, but with extra adjustment to justify ‘Chronometer’, ‘Special’ and ‘Superior Chronometer Special’ grades. The two ‘Special’ (35 jewel) movements also have fine adjusters on the balance.

The movements are part of Citizen’s 52xx/54xx family, which can be found in a range of their other models, for example the relatively well known Crystal Seven and the Seven Star lines, and the lesser known Crystal Date, Cutlass and Dandy Seven models. The 52xx line features both day and date windows, the 54xx line is date only. The Chrono Master movements are the 5240 and 5440 with 33 jewels, and the 5250 and 5450 with 35 jewels. No automatic Chrono Master model was made without date or date/day complications. The following family tree illustrates where they slot into the lineage:

The pricing structure (see later) also follows the degree of adjustment and therefore accuracy achieved at the factory. I have not been able to find any accuracy certification specifically for the Chrono Master, but I have included an example for Citizen’s 1962 ‘Chronometer’ in Part 1 of this article for reference.

The following table summarises the 52xx/54xx movement family by jewel count – interestingly, the 35 jewel Chrono Master is not the highest jewelled movement – that belongs to the 43 jewel Crystal Seven (5204) first produced in 1965:

The movements run at 18,000 beats per hour (5 beats per second), and measure 28.00mm across, and are 3.98mm deep (date only) or 4.38mm (day and date). They feature ‘second setting’ or ‘hacking’, i.e. the movement is stopped when the crown is pulled out to the time-setting position, to allow accurate synchronisation. The following schematic of the 33 jewel movement shows the balance with fine adjuster for the 35 jewel models in the box at bottom left:

As with its hand-winding namesake, all but one version of the automatic Chrono Master models, which are all cased in stainless steel, feature a gold medallion on the case back. There were no gold plated or gold-filled Chrono Masters, only the solid gold versions of the hand winding model as described in Part 1. The day window on the 5240 and 5250 models is oval in shape.

The dial markings, other than the Citizen logo and Chrono Master (showing upper and lower case printing as appropriate) for each model are:

5240 – AUTODAYDATE, 33 JEWELS + polished steel emblem

5240 – CHRONOMETER, AUTODAYDATE, 33 JEWELS + polished steel emblem

5440 – AUTODATE, 33 JEWELS – + polished steel emblem

5440 – CHRONOMETER, AUTODATE, 33 JEWELS + polished steel emblem

5250 – special, AUTODAYDATE, 35 JEWELS + gold plated emblem

5250 – SUPERIOR CHRONOMETER, special, AUTODAYDATE, 35 JEWELS + gold plated emblem

5450 – special, AUTODATE, 35 JEWELS + gold plated emblem

5450 – SUPERIOR CHRONOMETER, special, AUTODATE, 35 JEWELS + gold plated emblem

5240 Auto Day Date, lug width 18mm?:

5240 Case Back, marked ACSS2929, also found with case number 4-520840:

5240 Movement, with movement serial number:

5440 Auto Date, lug width 20mm – case number AUDS2910 or 4-540247:

5240 Auto Day Date Chronometer, lug width 20mm – case number ACSS2929 or 4-520840:

5440 Auto Date Chronometer, lug width 20mm – case number AUDS2910 or 4-540247:

5250 Auto Day Date Special, lug width 18mm?, showing fine adjuster on balance (note movement serial number on the rotor) – case number ACSS3014 or 4-521421:

5450 Auto Date Special, lug width 18mm? – case number AUDS3002 or 4-540301:

5440 Auto Date Special Case Back:

5250 Auto Day Date Superior Chronometer Special, lug width 18mm? – case number ACSS3014 or 4-521421:

5250 Auto Date Superior Chronometer Special, lug width 18mm?, note ‘Superior Chronometer’ is printed immediately below the Chrono master logo – case number AUDS3002 or 4-540301:

Original Prices (1967) – in Japanese Yen:

5440, 33j Chrono Master (date)


5440, 33j Chrono Master Chronometer (date)


5240, 33j Chrono Master (day/date)


5240, 33j Chrono Master Chronometer (day/date)


5450, 35j Chrono Master Special (date)


5450, 35j Chrono Master Superior Chronometer Special (date)


5250, 35j Chrono Master Special (day/date)


5250, 35j Chrono Master Superior Chronometer Special (day/date)


In 1971, catalog prices had remained the same (note the two prices for the models on a steel bracelet where this was an option – these also have 20mm lugs):


The Chrono Master Chronometer Diver, 1971

One more version of the automatic line was produced, in 1971, in the form of a diver depth rated to 500 meters. This is a very rare piece, using the 5420 date only movement with 33 jewels. The dial is marked ‘Chronometer’ and ‘auto date 33 jewels’ has been replaced with ‘PARA500mWATER’ and ’33J’.

The one piece case has a stamped emblem on the back rather than a gold insert, and is marked 4-540263.

Here it is shown with a price tag of JPY35,000 in the 1971 catalog:

The X8 Chrono Master :

First produced in 1969 as part of the ‘X8’ electro-mechanical watch line this model was a more developed version Citizen’s pioneering ‘Electric Watch’ of 1966, using the 0802 movement. In these watches the traditional mainspring is replaced by a battery and integrated circuit, which then powers a conventional hairspring balance albeit fitted with magnets.

Although the 0802 movement ran at 18,000 beats per hour powered by its 1.5v battery, the subsequent ‘Cosmotron’ models using later hybrid movements ran at 36,000 beats per hour, and in one case 43,200 beats (i.e. 12 beats per second).

The 25 jewel 0802 movement had only a short production run, reflecting the rapid development of the technology. However, the use of the Chrono Master name, and later other X8 models which were labelled ‘officially certified chronometers’, indicate their ability to run very accurately, at least within the parameters of fully mechanical accuracy standards.

The distinctive case shape, which won a Japanese design award when it was first produced, was shared with the original Electric Watch version. Two versions were made, the Chrono Master and the Chrono Master Chronometer:

0802 Chrono Master:

0802 Chrono Master Chronometer:

0802 Case Back & Movement:


Part 3

Dials, Logos and Hands

The Citizen Logo:

Three styles of applied logo were used, note the distinctive and unique font used for ‘Chrono Master’:

Dial & Hand Set Design:

The standard Chrono Master dial is pale silver with polished steel baton hour markers which have a black centre line. This style is repeated on the main hands, which are of a fairly narrow non-tapering design. The black centre line runs the full length of the hands. Second hands are steel and are generally the same on all models, tapering to a point from a long tail, reaching about half way along the hour markers.

There are two types of hour and minute hands on the main range – one type, which appears to be used primarily on the hand winders and the date only automatics has a more pronounced point, with no ‘tail’ i.e.:

On the day and date automatics the point is very stubby, and at first glance the hands can almost appear to have square ends, and they have a ‘tail’, i.e. they stretch beyond the centre hole:

The hour markers and main hands on the 18K gold Chronometers look to be similar but narrower, whilst the second hand looks longer although this may be the result of the use of a smaller dial.

Exceptions to these styles seem to be:

1) the dauphine style hands on the Chronometer hand winder – this image is from a reliable source so I presume these are correct:

2) the lumed hands on the 500m diver, with Mercedes hour hand and squared framed lume on the second hand:

The diver is the only black dial in the Chrono Master line-up as far as I know – I have seen one Auto Date model with a black dial but it looked to me to be a re-dial. Not only was it black, not seen in any catalogs, but also the positioning of the dial text was not quite right, at least in my opinion.

3) On the X8 Chrono Master the hands are wider at the centre and slightly tapered, with a black centre line running about half way along the hand and not reaching the points, and these may be unique to this model – the second hand has a spear shaped tail, and can be seen on some other older models, for example the 1958 Auto:

Part 4

Other Models

I have seen three other Chrono Masters which don’t fit the above descriptions, none of which I can verify as authentic models, but I include them here as at least being of interest and potentially correct original pieces.

First is this day and date ‘Elite Special’ – it appears to have a unique dial, so perhaps this is a legitimate special edition:

The 4-520840 case back is correct for the day/date type:

The movement has a serial number indicating that it is the chronometer version of the 33 jewel movement.

Second is this blue dialled model, with different logo at the 6 o’clock position (also seen on export models, but with different movements). I think I have seen two of these:

Again the case number – 4-540247 – is correct for a date only model:

Finally, this last one is very interesting – unfortunately I haven’t got a dial shot other than a thumbnail, but I think it was a standard Chrono Master dial:

As can be seen it is marked ‘Hanmi Citizen Precision Ind Corp’ which was the name of the factory Citizen established in South Korea in 1974, later known as Citizen Precision of Korea Co., Ltd. The quality of the back suggests to me that this is an authentic piece.

(Acknowledgement: some images are from the internet, and I am unable to attribute them. If you recognize any as your own please let me know so I can seek permission to use them, or remove them if not given)



37 Responses to The Chrono Masters

  1. Thanks for the research and invaluable reference material; I have acquired four chrono masters, as follow: 1. a 25j Chrono Master date, HOD50291-Y; 2. a Chrono Master , auto daydate 33 jewel, AC552929-Y;3. A Chrono Master auto date 33 jewels, AUD52910-Y and 4. a Chrono Master X8 Electronic, ELCS 5021-Y; you might be interested to know I also have a Citizen Chronometer, Officially Certified Automatic Super Beat 10, 4-740041 Y; and finally a Citizen Crystal 7, 43 jewel AC552924-Y.

    Stephen Loomes

    • sweephand says:

      Hi Stephen, you have a very nice collection 🙂 Sorry to be pedantic, but can I confirm that the case numbers on yours are HODS2901, ACSS2929; AUDS2910 and ACSS2924? The ‘S’ does look like a 5 on the case backs! Great to have the Super Beat Chronometer, that’s at the top of the range in the Leopard line up. And the 43 jewel Crystal Seven was Citizen’s highest jewelled model 🙂


  2. Russell I says:

    It has been a bunch of years I read your Post. Having a very nice 1968-69 Vintage GS 6146- 8000 to 8040 collection Few keep the Accuracy of my Chrono Master Day/date Special 35 J -AC55–Y4
    The date window is above at 12 date at 3 Just Love her.

    I have a really nice Crystal 7- 43 J but she needs some Crown attention .

    Thank you for this article it has addressed Questions I have had for a long time, your
    efforts are very much appreciated


    • sweephand says:

      Hi Russell, it’s great to hear form you and thanks for visiting my blog 🙂 Good to hear that you are impressed with your Chrono Master and that it compares favourably with your vintage Grand Seiko’s. I’ll be updating and uploading Part 2 of the article soon, so I hope you have time to take a look at that.

      What is the problem with the Crystal Seven crown?


  3. Thanks for the reply Stephen, and again, your research is a godsend; you must be right, I could not distinguish whether it was an “S” or a “5”,
    cheers from one of your Australian followers.

    • sweephand says:

      You’re welcome 🙂 I might do a page on how to interpret the earlier style case back codes, for example ‘ACSS’ = Automatic; Crystal (i.e. hardened mineral glass); Seven (i.e. includes date and day complications); and Steel.


  4. marvin says:

    Hi Stephen, I appreciate the great research and compilation that you’ve accomplished. It will surely be used by collectors and enthusiasts for years to come.

    I’ve been looking at a basic ’67 22J/ 0920 hw Chrono Master. It has a ‘CTZ” crown. Based on your work it is likely a replacement, especially since the dial is a nice repaint. Condition looks very good otherwise, with very clean movement but moderate gold medallion wear.
    In your opinion do those refurbishments reduce the value much? Rather than (emotionally) overspending on this one the money could be used toward a high end modern Citizen GS-equivalent import.
    Do you think the CM 0920 would be up to the challenge of everyday use?

    One more question … I have a nice leopard 8 that auto-winds well, but does not wind manually. Assuming that it should (!), is the repair fairly straightforward to do?

    Thanks again for your generous research legacy.

    • sweephand says:

      Hi Marvin, thank you for your kind comments, much appreciated. A dial repaint and the worn medallion on the Chrono Master should reduce value site substantially I would think – hard to say exactly though, and someone who hasn’t researched the model may pay over the odds. To a collector it would be significant, although a collector would probably pass on it anyway I suppose. The case looks to have been polished which has taken off some of the crispness of the angles. Although the dial repaint looks well done, it looks to me that the restorer has put the hour markers on the wrong way round – the bevelled end should be on the outside on this model I think – compare to this catalog pic:

      Although there’s clearly a place for well restored pieces that otherwise would have been in poor condition, restorations need to be error free! I saw a ‘Center Second’ model with a re-finished dial, which looked very nice except the text was spelt ‘Senter Second’….

      It’s your decision of course, but personally I would pass on this one.

      As to the Leopard, as far as I know all models should hand wind – does the crown moves freely in both directions, and can you hear any clicking as you turn it especially anti-clockwise? I’m not a watch maker but I can make enquiries for you. Which model do you have?


    • sweephand says:

      Hi Marvin – I should have said in my first reply that I think the Chrono Masters should be good for everyday use, providing they are running accurately, so not already showing signs of significant wear, and have been fully serviced by a skilled watch maker. The CM movements run at 18,000 beats per hour, so are not as susceptible to wear as the high beat models like your Leopard, so they should be OK for regular use providing they have been well looked after.


  5. marvin says:

    Wow, thanks Stephen. I’m disappointed, but grateful. You saw the one I was looking at. Handsome design. The markers didn’t feel quite right, but I failed to notice they were reversed! My eye isn’t yet as sharp as it needs to be to comb through these old watches. It should have been obvious. You’re also correct on the polishing job – it hides the wear but softens the original design appearance. Rather than spending the (assumed) $350-450 on a faulty restore it would be better put toward another worth collecting. Thanks for the schooling.
    On my Leopard, my favorite, it’s a 1971 Super Beat 8 /26J. 4-7600!B Y, 10321667, GN-1-S. (I’d be happy to send you pics if you send your email address.) The old metal band isn’t original to the watch but is serviceable until fortune turns up an original.
    It needs a good service, seals, etc. despite what a seller indicated, although the accuracy seems good. The outer case is a bit dirty which may be a positive, since it wasn’t polished to death. The stem functions easily and smoothly clicks anti-clockwise, but will not turn clockwise with firm pressure.
    Thanks for the patient advice. Marvin

    • sweephand says:

      You’re welcome Marvin 🙂 I think you’re right about putting the money towards a better example.

      My 4-760018 Leopard is a fairly close relative of yours – the serial number is 10320791. Should definitely hand wind, and since it’s stuck in the clockwise direction, there is obviously something amiss but I’m not a technician so I can’t help any more with diagnosis! Since the watch is running well otherwise, hopefully it is a relatively minor problem, and it is still perfectly usable with auto-winding. If you do send it for service / repair make sure you find a skilled watchmaker who is used to working on vintage mechanicals.

      I’ll email you for pics – I always like to see other people’s Citizens 🙂


  6. Miguel Mendoza says:

    Hi, very lovely and informative page. I bougth a chrono master in a flea market in Mexico city. Some people say in the internet that is not real but with your page I find that a 27 jewels calibre 5003 exist with 27 jewels as it’s mine. But The dial on my day date waych say 33 jewels and the day is in Spanish. I really can’t find if this watch which I fell in love at the moment I saw, is real. I’ll try to send pictures if let me so, Thanks very much.

  7. Miguel Mendoza says:

    Where can I sen pictures?

  8. Ronald Yu says:

    Does the Chronomaster Special auto day date 35 jewels model come with the strap with leather insert on buckle?

  9. Stephen,

    Could you advise if all the date models have quick set date function?

    Looking at getting one of my own.


  10. Ronald Yu says:

    Is there any difference in the movements of ” Chronometer ” and ” Chronometer Superior” ?

  11. Eric Fauser says:

    I’m wondering about a ’67 H005 3002-Y I have. All seems correct except there is no serial number beneath the jewel count. I find that curious and don’t see anything referencing that (although I may have missed it).

    • sweephand says:

      Hi Eric, thanks for visiting my blog and apologies for my later reply – I was away from home all last week. The HOOS 3002 Chrono Master dial doesn’t have a jewel count, and should have ‘JAPAN@ + the dial code printed under the 6 o’clock marker. It’s possible yours has been refinished. It would be helpful to see pics of your watch, have you any pics uploaded which you can post a link to? Or I can email you if you prefer to send pics to me, just let me know. Stephen

  12. Pingback: #TBT The Citizen Chrono Master - A Vintage Alternative to King Seiko

    • sweephand says:

      Hi Eric, thanks for clarifying that 🙂 I haven’t got a reference pic showing your movement (0920) without a serial number, but my Chrono Master reference page does show one of the 1870 movements with no serial number. This suggests that it is nothing to worry about – your movement looks absolutely correct otherwise. The non-chronometer grade pieces are likely to be the only ones without a unique number – I would expect any chronometer graded pieces to have one. Stephen

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.