Twin Crown Diver from 1970

In the wider world, Citizen is maybe not so well known for its vintage mechanical watches, and particularly for their divers made from the mid 1960s and through the 1970s. Although there’s a page on this blog which describes the various divers ( there is sometimes a little detail or two to add. And with many thanks to Bill,  a visitor to my blog, I am able to add a little bit of information on Citizen’s twin crown range.

Rated at 100 meters, although not a ‘compressor’ diver  Citizen’s design has a similar look  – two crowns, one to wind and set the watch, and the other to move the inner rotating ring. As far as I know they were produced around 1968 to 1970, using the 5270 automatic movement, a variant of the 52 series of calibres first produced in 1965. This was a very successful family of movements, used in two of Citizen’s better known ranges, the Crystal Seven and Seven Star, as well as high end Chrono Masters and some less well known models – see here for a ‘family tree’:

Typical of its day, the movement runs at 18,000 beats per hour. The 5270 variant has 21 jewels with date / day complications, quick setting for the date only, and no ‘hacking’. Japanese domestic market models carry the ‘Seven Star’ and ‘parawater’ monikers whilst export models lose the model name and are marked ‘waterproof’.  There were several dial colours – black, blue, silver and red. And this brings us to Bill’s example – a nice example of the black version:


The ‘Mercedes’ hour hand is typical of these, although occasionally they can be found with a straight hand. I’ve noticed that the inner rotating rings, turned by the upper crown, seem to wear very well, even on examples where+ the dial itself is poor. Note the dial code below the six o’clock marker – the presence of a correct dial code is a good sign of originality. Also note the radial brushing on the upper face of the case and well defined angles and curves, which show that the case has not been polished.


The two crowns are identical, and are signed, with ‘CTZ’ on this example, or with ‘C’ on others. The case measures about 42mm across, and is comfortable on the wrist. The acrylic crystal sits high on the face of the watch:


The screw down case back is typical of Citizen pieces from this era:


Note that the back is stamped ‘parawater’ rather than proof – this is not that unusual and is not of concern when considering correctness. The case number – 4-520343 – is clearly marked, and the serial number (00321363) gives a production date of March 1970 – from the first three digits. And this brings us to the new piece of information: most of these models have the case number, but no model number, but on this one a model number is stamped on the back – 61-5111.  This is something I can add to the diver reference page.

Many thanks again to Bill for sharing his watch – all photos are his and should not be reproduced elsewhere without permission.

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17 Responses to Twin Crown Diver from 1970

  1. Thanks again Stephen for increasing the invaluable fund of reference and knowledge you have created for us, the collectors; it must be getting near time for you to amalgamate and publish a hardcopy reference work of all your research so that we can have it on a shelf.
    kind regards
    Stephen Loomes

  2. Dan says:

    Great post as always…. But I do not think this is a Compressor Case. Firstly 2 crows do not make a compressor, as compressor refers to the case – there are many compressor cases with single crowns – see Enicar. A real compressor case was made by EPNS (Ervin Piquerez S.A.). Most make the mistake and call all two crown cases, compressor – this is incorrect. Compressor and Super Compressor refers to a patented case sealing method developed by watch case manufacturer Ervin Piquerez S.A. (EPSA). The design takes advantage of the water pressure the case is exposed to at depth to press the case back against the O-ring seal. More depth equals more water pressure equals greater seal.

    • sweephand says:

      Hi Dan, thanks for your comments. I didn’t mean to say that this is a compressor case, but I realise that my wording was a bit ambiguous, so I’ve now changed it to be more clear 🙂 Stephen

  3. Kiljunen Mikko says:

    Great information as usual Stephen!

  4. Sue says:

    Hi. I have recently acquired a vintage Citizen Ladies watch. back cover has
    on it. Can you please tell me if this is worth repairing? it is a wind up and has the 12;00 mark loose inside face which tends to stop the hands at times.
    Thanks to your blog i have managed to find that is a White Gold plate
    It is silver/metal with square glass face with each corner cut off. I have tried to find it on the web
    but have not turned up anything yet as to age, value or wether it s worth fixing. Thankyou and hope you can help. i will continue to try and find some answers. cheers

    • sweephand says:

      Hi Sue, thanks for visiting my blog. Although you describe your watch as a wind up, I understand that the 6800 movement is a quartz model – that is also consistent with the case and model numbers you’ve got. Citizen has made many thousands of quartz models over the years so it is hard to find info on specific ones and my reference info is on the early mainly mechanical watches. I would think yours is from 1985. I’m afraid that quartz watches have little value, unless they are particularly rare early ones, or very high end. Stephen

  5. Celeste says:

    Hi sweephand, I have a lovely rectangular Citizen quartz, which I had repaired and cleaned. No’s 6010-K02341 OK, 3020327 serial no. I think.. GN-0-S, 12 which is the number of quartz or little stones on front. Japanese movt. I just want to know year of its manufacture. And why only 7 numbers? Thanks so much, Sally

  6. Juan Ferrandiz-Santos says:

    I am looking for a crown replacement to this piece: Vintage Citizen compressor style diver 4-520343Y which movement is the automatic Citizen calibre 5270…er-4-520343-y/
    It is a dual crown model, but some models that I have seen have two crowns with “CTZ” logo and other come with one “CTZ” crown and other with the “C” logo. So, my questions are:
    -Which kind of crowns must be fitted in this piece (2 “CTZ” or 2”C” or 1”CTZ”+1”C”)
    -Which is the proper numbering of them, in order to find them out in the market?
    Thank you so much in advance

    • sweephand says:

      Hi Juan, thanks for visiting my blog. As far as I know both the earlier ‘C’ and later ‘CTZ’ crowns are correct on the 4-520343 diver, but originally they would be one or the other, not mixed. When the two styles are mixed, I would think it’s most likely that the winding crown has been replaced, and the later CTZ crown would have to be used. So it would be best to get two matching crowns if possible. The original part number is 506-139, but I’m not aware of any sources for it these days I’m afraid, other than keeping an eye on sales on Yahoo Japan, or finding a donor watch – there are other models that used this crown so let me know if want a list of them, although one is a Chrono Master so that may not be the source of a cheap donor!

  7. Juan Ferrandiz-Santos says:

    Thank you so much for your time
    Excellent suggestions

    • sweephand says:

      You’re welcome Juan 🙂

      • Juan Ferrandiz says:

        By the way, I was thinking about your last recommendation (“…other models that used this crown….”). So if you don´t mind, would you please let me know a list of them (cheapers donors…), just in case I do not find out an original part number
        Thanks in advance

        • sweephand says:

          Hi Juan, here are all the case numbers for crown part number 506-139 that I can find in my reference material. All of them have the earlier type of number (e.g APSS52802) and I’ve included the later type as well where it’s available (e.g. 4-521349). I’ve listed them against the model range that I think they are part of, plus the odd note to help (I hope!):

          Crystal Seven: ACSS2801, ACSS2830 (4-521366), ACSS2901/2902/2903/2904 (4-520459/4-520475/4-521625), ACSS2905, ACSS3001, ACSS3003, ACSS3004, ACSS3005, ACSS51301, ACSS51401 (4-520394), ACSS51402 (4-520645), ACSS51403, ACSS51404 (4-521170), ACSS81301, ACSS81302 NB: The Crystal Seven range may be the most likely source of a donor, but I don’t know how rare the models listed here might be.

          Seven Star: APSS3001, APSS52701, APSS52801 & 52802 (4-521349 / 4-521552), APSS52901/52902, APSS3101,

          AutoDater, AutoDater Seven & Crystal Date: ADSS & AUDS2801, AUDS3101, AUDS52901, ADSS1302, ADSS81303, ADSS81304, AUDS52701/52702/52703 NB: I’ve seen these with no signature on the crown, although they share the same part number as your diver

          Chrono Master: HOOS2801 (4-020201) – a very collectable watch so not a realistic donor watch

          Yahoo Japan might the best option, although it carries some additional costs than eBay – for example here is one of the Crystal Seven models for sale at the moment:


  8. Juan Ferrandiz says:

    Absolutely impressive
    Stephen, thank you so much for the information

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