Longines Chronometers

Is there not a pic of the dial with "chronometer" clearly written on Valjoux72's post ? From all I know about Longines, all of their watches that were marked as chronometers on their dial, at least between 1930 and 1951, were actually independently certified, by observatories or Bureaux Officiels.
But yes you're right, movements with just adjustments marking were not chronometers, and btw it's strange if Valjoux72's watch really is a chronometer that there's no mention of temperature adjustment... It seems there was a private conversation between you all so I may not have all elements here, just some teases, I'd love to know more as a fellow Longines chronometer collector !

I believe that the dial has been refinished. I have seen another 22N with a close serial number, 5 ADJ. marking, and an original dial and it is not marked "chronometer". So, I think that the dial restorer was feeling creative.

I am not sure that Longines made between 1930 and 1951 that were marked "chronometer" on the dial were all tested at an observatory. I am sure that some were since this was attested to in period advertisements, but I wonder if some were not.

Ok, here we go.
Longines chronometer signed watches from the 1940-50s are extremely rare. Most of them had large 14.68z and 15.68z movements and 18k gold cases. Due to Tony's fantastic research in the "lady luck article" he has published a few years ago here, we know Longines sold smaller Chronometer signed wristwatches with certificates at the beginning of the 1950s.



This swiss advertising from around 1950 shows one of these watches.

The one I have got from a german collector who had the watch in his collection for more than 20 years, shows some similarities.



Dial design and hands are the same, both have a chronometer signature on the dial and a 18k gold case.



The movement is signed with 5 Adj. Longines told me that the watch was sold in spring of 1949 to Streuli, which were the partner in China at that time. Very interesting sideline as this was just a few monthes before the communist party took over the power in China.

Unfortunately Longines doesn't have any further Information about the movement to share. Maybe it wasn't one of the certificated chronometer watches or they just sold the watch with all the original papers...
Discussed the watch with some of our best Longines experts here on OF in a private conversation.
We are not sure about the red Chronometer inscription, that might have been added later. Nevertheless I'm very excited to add this watch to my small Longines collection.

At an observatory or bureaux officiels, there's evidence Longines sent watches to the bureau of St. Imier in the 1940s.
Tbh I'm not a hundred percent sure either, but there's two things that makes me believe so : for one, their catalogues and sales brochures of this era stated they were officially tested (see here the 1929 and 1937 brochures, while the earlier 1916 one clearly had an option for in-house tested "fabrik" chronometers), and for two Longines chronometers are so rarely seen I believe they easily match the known figures of tested watches from observatories and bureaux reports...


I admit it seems somewhat fishy. Rumar89 may have told you this, but according to his archives only 6 Longines wristwatches were tested at the bureau of St Imier the year yours was sold, and none the precedent year when your watch could have been produced, so the chances yours is one of those six is extremely low but not impossible either !

The watch below is supposedly a caliber 12.68Z that was invoiced to Argentina in 1941. To me, the "chronometre" printing looks quite good but I am inclined to suspend judgement on whether the movement was tested by an observatory or bureaux until I see more evidence. Maybe the fact that the watch went to Argentina is significant.

The fact it was sold to Argentina plays in its favor, as a good part of Longines' most high end watches were sold to this market (I have an observatory chronometer and a 27.0s sold there). One good hint it may be an actual chronometer is if the 12.68Z inside has a breguet overcoil, do you have pics of it ? To my knowledge, only british military "www", rare 1930s silver cushion watches for the british market and chronometers had a 12.68Z with the overcoil, a quite rare feature.

@707mm2 Unfortunately, I do not have a photo of the movement. With regard to hairsprings, many American market Longines (9L, 10L, 12L etc.) from the period also had Breguet overcoils.

Wrong, The first Bureau Officiel started as early as 1877 in Bienne, and wristwatches were already tested in significant numbers in the 1930s. What happened in 1951 is that it became obligatory for a watch to bear the "chronometer" mention to be tested in these bureaux or at the observatory. In any case, before or after 1951, a lot of officially tested watches just had "chronometer" or french "chronomètre" on their dials, the "Officially Certified" mention is mostly a catchy sales argument. (see Von Osterhausen's book on chronometers for reference)


I know, but note that none of them is a 12.68Z... Again, and I speak of this caliber in particular, the overcoil is a very rare feature on the 12.68Z. I have seen in the past at least two 12.68Z chronometers, and those two having this very rare feature let me believe they were the real thing. If one would like to fake a 12.68Z chronometer, I can difficultly believe he would have bothered to find such a rare movement instead of just taking one of the hundreds of thousands flat spiral movements.

You are right. There are lots of 12.68Z variants (12L, 12.68N, 27.O) that have Breguet overcoils, but not many "12.68Z" with them.

Regarding whether a given Longines is a chronometer, I think that it should be mentioned in the archive. To me, movements that are marked "5 ADJ." are neat (I have a 10.68Z from 1942 like this), but they are not chronometers unless there is some indication in the archive about independent testing.

I wonder if you have more information about the 12.68Z chronometers you have seen? Were they wristwatches, were the dials marked "chronometer", where and when were they sold? Thanks for the discussion.

Yes I have, one of them was offered on chrono24 but I can't remember when or for which price, the other on the bay when I started collecting Longines around 15 years ago, again can't remember the price but Longines did not sell much then I can tell you... They were both marked "chronomètre" on the dial, luckily I saved the pics of the chrono24 one but I don't know if it's ok to share them ? No copyright infringement ?

Thanks for sharing your immense knowledge with us. Should not be a problem to share an old C24 or Ebay pic here...

I hope you're right... Well, let's try ! I already made a private mail to DirtyDozen12 with the info so I'll try to expose this in a better way maybe.

So first here's the 12.68Z chronometer I spotted :



There's at least two hints that drives me to believe it's genuine and was actually tested by the Bureaux Officiels. First, the movement's finish is unlike anything I've seen on other variations of this calibre. As I said, almost impossible to fake this, this movement is certainly one of the rarest 12.68Z variations. For comparison, I've included the only others 12.68Z with a Breguet overcoil I know of (well almost, but there's no need to include the stop second/chronograph versions for obvious reasons). From left to right, you have a 1930s Baume, an observatory chronometer and a british military WWW both from the mid 1940s. The Baume has the same finish as a 1930s 27.0 caliber but with the 12.68Z typical bridge layout. On the other hand, the observatory chronometer has the same bridge layout than the 27.0 (but was still curiously marked as a 12.68Z) but with a much better finish (Guillaume split balance, counter pivots on the escapement wheel and beveled anchor - only later 27.0(S) movements from the 1950s had a beveled anchor). Lastly, the WWW has the most basic finish of all, with only 15 jewels and no beveled steel parts (not even the regulator), but it's the only one to feature a shock absorber.



The 12.68Z B.O. chronometer (to differentiate it from the observatory's version) is clearly a unique variation : it has nickel plating with geneva stripes and a curious combination of higher and simpler finish, but in a such coherent way it can't be a franken (for example, the ratchet is highly polished and bevelled like on a 27.0 or early 12.68Z, but the winding wheels are still the plain ones found on classic later 12.68Z, or the hairspring stud is not beautifully screwed like a 27.0 of the same era, but the regulator still keeps the same high finish). Here's another chronometer to compare the finish, but because this one is in a gold case, as it was pretty usual with Longines then, it's not a 12.68Z but a 27.0 :



You will note this 27.0 has, like its balance wheel, a beryllium bronze anchor, a common feature of fine 1940s to early 1950s Longines. The 12.68Z BO chronometer pics I have here are not good enough to see if it has it too, but I clearly remember the other 12.68Z BO I have seen long before having this particular feature.

Now for my second hint, it comes from the serial number. From what I can read, the 27.0 and 12.68Z BO seen here are... consecutive ! It seems they were made just one after the other ! (Believe me, this really is pure luck, I spotted those watches in different times on different sellers - the 27.0 was sold on Time Titans - and actually only noted this today while writing this post...). Moreover, they point to 1950, a year which Longines submitted to certification much more wristwatches than usual (exactly 66 wristwatches submitted to the B.O. of St Imier if you exclude automatic movements, previous year only 6 were submitted and following year only 5).

If you put all this together, I think the two chronometers presented here are extremely likely to be genuine, don't you think ?

I agree, and since we have pics and serial numbers it would be easy to ask to Longines what is in their archives, but I feel misplaced to do it, to me only the owners should be able to do this and I hope one of them would manifest and participate reading this, even if it's very unlikely. I wish more collectors would be willing to share such important pieces. Maybe one of you is close enough with Longines kind curators to feel asking them about the records of these watches ? I could pm the exact serial numbers to anyone willing to if you can't read well enough on the pics.

Just to be clear, the only thing that I find remarkable about the 12.68Z chronometer movement above is the balance assembly, which resembles that of a caliber 27.0. Below (left) is a caliber 12.68Z that looks very similar, apart from the "17 Jewels" marking and the balance assembly. Also below (right) is a caliber 27.0 with the same balance assembly, apart from the absence of Geneva stripes. I am not trying to imply that such a difference is insignificant in terms of whether or not the watch is a chronometer, but I think it would be useful to be specific.



As for the 27.0 chronometer above, the only thing that I find potentially remarkable is the combination of a mono-metallic balance wheel with a steel-capped stud holder. Below is a non-chronometer caliber 27.0 that looks very similar to the 27.0 chronometer, apart from the balance wheel and color of the anchor. As a side note, is there documentation to confirm that gold-colored anchors are made of beryllium copper? Given that steel anchors were used on earlier observatory chronometers (like the 12.68Z above) and later 27.0S and 30L chronometers, I wonder what the significance of a beryllium copper anchor would be? Another side note, I believe that Longines' silver-colored movements were rhodium-plated during this period, not nickel-plated.



Finally, as @Tony C. wrote above, the most important piece of information is confirmation from Longines' archive. The 12.68Z and 27.0 chronometers above certainly look genuine, but the question remains whether or not they were independently tested. Given the close serial numbers and the fact that the 27.0 is a reference 6215, which is depicted in an advertisement as a "chronometer with certificate", I expect that they were. For confirmation, I contacted Longines yesterday with photos of the reference 6215. I will report back with the results.

My bad, you might be right !


Actually, this is not unique to this watch, some non chronometers 27.0 of this era show similar finish. Beside the marking on the dial, there is most of the time no way to differentiate chronometers from "basic" 27.0 of the same era. This caliber was already in its common form the highest finish you could find on a 12 lignes Longines.


Anthony G. Randall writes about this in one of its book, I don't remember if it's in his Catalogue of Watches in the British Museum or in his Time Museum Catalogue of Chronometers, sorry for my not very fresh memory. After 1937 (the introduction of the glucydur balance if my memory's correct) numerous brands experimented with beryllium escapements (sometimes both the anchor and escapement wheel were made of this). Apart from Longines, I've seen it also on Movado, Solvil and more famously Patek Philippe. It was mainly used for its non magnetic properties, as illustrated by the famous PP ref.3417 Amagnetic (see this antiqorum listing, clearly stating the use of bronze beryllium instead of most lazy auction houses stating solid gold escapements in this reference, a very poor choice for a performant escapement...), but was abandoned, as explained in this PP watchmaker's manual (for those who read french), around the early 1960s because its performance was still less than traditional steel :

@707mm2 Thank you for the information on beryllium copper. Interesting that the steel parts ultimately performed better.

Longines responded and stated that the ref. 6215 (posted above) received a bulletin (1st class) from a watchmaking school. The watch was invoiced to Wirth (Switzerland) on December 7, 1950.