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Longines with 25.17 caliber

BlueHarp
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BlueHarp WRT Addict

BlueHarp

Posted
Posted

Hi all of you,

I had an opportunity to buy a vintage watch early in the morning. It is supposed to be a Longines with a 25.17 movement. As there are some buyers who react very quickly when they see a new watch on that website, I had to make my mind at once. I made some researched immediately, and then I decided to get that watch. After that, I made some additional research, and I think it might be a real Longines.

Would you have the same opinion as you look at the pictures attached?

 

2d0ca5779cd24e03348b64bd078417c90f352d39.jpg

27bd4eaae3eee95be6b761141f1219bdc4012443.jpg

a8662caf674f3533e275c9a2187666efa75718c3.jpg

bec9b38652838ce162dc0a909ded97d11acc7a10.jpg

d868a9bde0d994d1b36ab4f3700ff2b1682c3b67.jpg

e434a4fe961bc14743412157bdf369f41789404f.jpg

BlueHarp WRT Addict

BlueHarp

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Posted

Does that mean it's a fake? I had a look on SERIAL-NUMBER-DECODER.CO.UK which confirms that the serial number 5472134 refers to 1936, but the website indicates that "I have estimated dates for years where I couldn't find any information so please consider this a guide only, it should be within a couple of years either way".

I had a try with another website which indicates 1937 and a third one which indicates 1936 (approximately). 

May I still hope that it's a real Longines? If not ... I've been to quick in my decision🥴

AndyGSi Distinguished Member

AndyGSi

Posted
Posted (edited)

It may just not be a 25.17 movement but I don't know enough about Longines to what came later.

Edit

Just found this which dates to 1935 so maybe the 25.17 was made before 1939 as stated on Ranfft.

https://www.joseph-watches.com/all-products/longines-cal-25-17-stainless-steel-1930s/

Re Edit

Done i little more searching and to me it looks like Ranfft is wrong
but can't find what actual date these were first produced.

Looking at other examples my thoughts would be it's a genuine movement but the dial
and case both look wrong so I suppose it all comes down to what you paid for it.

Edited by AndyGSi
mikepilk Distinguished Member

mikepilk

Posted
Posted (edited)

Longines have a service where you can send the serial number and they will tell you the date and name of the agent the watch was sent to. 

I'm not sure about the case, but I would expect "Longines" on the dial

Edited by mikepilk
  • Like 2
Nucejoe Distinguished Member

Nucejoe

Posted
Posted

I beleive Its a Longines, couple of variants to this calib were made,  one with flat and several  with overcoil H/S, overcoils were furthure modified, thus new designations.

 TG reveals it's  worth, when serviced. 

 

 

 

ClaudioCavalli Member

ClaudioCavalli

Posted
Posted
7 hours ago, mikepilk said:

Longines have a service where you can send the serial number and they will tell you the date and name of the agent the watch was sent to. 

I'm not sure about the case, but I would expect "Longines" on the dial

Yep,  used it and they are pretty fast!

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BlueHarp WRT Addict

BlueHarp

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On 4/10/2025 at 7:12 PM, mikepilk said:

Longines have a service where you can send the serial number and they will tell you the date and name of the agent the watch was sent to. 

I'm not sure about the case, but I would expect "Longines" on the dial

The thing is you have to provide Longines with a serial number AND a reference number when you fill the form. I have the first one on the movement, but I can't see the other one, which sould look like L.xxxxxxxxxx. I mentionned the number inside the case and I sent the mail. Wait and see...

Here are some picture I took yesterday when I received the watch. 

20250417_195820.jpg

20250417_200048.jpg

mikepilk Distinguished Member

mikepilk

Posted
Posted
7 hours ago, BlueHarp said:

The thing is you have to provide Longines with a serial number AND a reference number when you fill the form. I have the first one on the movement, but I can't see the other one, which sould look like L.xxxxxxxxxx. I mentionned the number inside the case and I sent the mail. Wait and see...

The number in the case (1444) is the reference number. On older movements it's a shorter number.

When I applied I sent the serial number from the movement and the reference number on the case back. In my case for a 1967 Cal 30L the case number was 7855.

BlueHarp WRT Addict

BlueHarp

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Posted

Thank you so much! So I think I provided the right information. I just have to wait now. I have disassembled / cleaned / reassembled the watch. Still alive 😀

Mercurial Watch Enthusiast

Mercurial

Posted
Posted

The movement is a genuine Longines calibre 25.17, and is the version with the flat hairspring (no Breguet overcoil). 

I’ll be very interested to see what Longines says about the case. It looks like a generic jobbers case and I think the movement was married with the case and dial after it left Longines. 

Best Regards,

Mark

  • Like 1
rehajm Super WRT Addict

rehajm

Posted
Posted

Did Longines contract ébauches to jewelers? Twas quite common to see branded movements sent out this way. Either way don’t assume nefariousness. Worst case you probably have an ‘unbranded’ watch with a Longines movement.

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BlueHarp WRT Addict

BlueHarp

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Posted

Oh, I see ... I'll just have to wait for the answer from Longines, and I will tell you.

When disassembling the watch, I noticed some figures on the back of the dial. I don't know whether they mean anything.

Thanks to all of you!

Longines 2517-4.jpg

mikepilk Distinguished Member

mikepilk

Posted
Posted
5 hours ago, Mercurial said:

’ll be very interested to see what Longines says about the case. It looks like a generic jobbers case

The format of the numbers on the case back are similar to Longines I have - a two digit and a four digit number. 

4 hours ago, rehajm said:

Did Longines contract ébauches to jewelers? Twas quite common to see branded movements sent out this way. Either way don’t assume nefariousness. Worst case you probably have an ‘unbranded’ watch with a Longines movement.

The lack of "Longines" on the dial suggests this might be the case. But then you would expect the jeweller to put their name on. 

We await the response from Longines. 

BlueHarp WRT Addict

BlueHarp

Posted
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Posted

Bad news: Longines doesn't provide this service free of charge any longer. I have to ask for an extract from the archives or a certificate of authenticity, but I'm afraid it's not worth the cost for this watch.

Too bad 🥴

  • Sad 1
rehajm Super WRT Addict

rehajm

Posted
Posted (edited)

Unfortunate…but you clearly have a Longines branded movement with a year 1936 serial consistent with the caliber. I checked the case maker of the last few Longines I worked on…

image.thumb.jpeg.ce0fd2c41eb5bf817509c7185c983ee1.jpeg

image.thumb.jpeg.375e5393cbfc9fd809a7d63790d9d0f7.jpeg

…same as your watch, so certainly you have grounds to honestly describe your watch as a Longines cal 25.17 tank with unbranded dial…and given the modesty of the watch IMO the Longines authentication wouldn’t dramatically alter the value, if that’s what you are hoping…as nucejoe suggests the value will mostly be determined by how well it runs…

Edited by rehajm
BlueHarp WRT Addict

BlueHarp

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Posted
19 minutes ago, rehajm said:

…as nucejoe suggests the value will mostly be determined by how well it runs…

It works quite well. The only strange thing is that it loses 2/3 mn per day whereas the measurements indicate that it is fast by 1/2 mn. Maybe something wrong with the gear mechanism ...

Mercurial Watch Enthusiast

Mercurial

Posted
Posted

How do the timegrapher readings look after the watch has been running for 24 hours?

Are you using a phone app or a dedicated timegrapher to take your measurements?

Best Regards,

Mark

BlueHarp WRT Addict

BlueHarp

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I don't have a timegrapher. I have two ways to check the accuracy of my watches :

* First I have the app Watch Accuracy Meter

* Then I take a real measurement everyday at the same time, using timeis.com website

That double check works very well with my other watches (Seiko 5, Herma / Parrenin HP X40, Lov / AS 1710/11). Both the app and the real measurement indicate approximately the same thing (the app is a little optimistic). The Longines is the only one for which the app tells me it's fast whereas the real measurement every 24 hours indicates it's a little slow. That's why I guess the problem could come from another part than the balance wheel.

Mercurial Watch Enthusiast

Mercurial

Posted
Posted

Apps like Watch Accuracy Meter can be inaccurate, and will read some watches better than others. 

What daily rate does Watch Accuracy Meter give you if you check the Longines once it’s been running for 24 hours?

Best Regards,

Mark

BlueHarp WRT Addict

BlueHarp

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19 minutes ago, mikepilk said:

A quick Google for Longines 25.17 found several similar watches - like this one with writing on the case back similar to yours

https://benjaminmarcello.nl/product/longines-cal-25-17-tank-from-1938/

 

Very interesting!

I answered the mail from Longines, explaining that I was a bit disappointed and that I wouldn't ask for a costly confirmation for a watch which isn't a high-end one ... and I received another email explaining that they couldn't not certify the authenticity of the watch, but they could specify that, according to the serial number on the caliber and to their handwritten records, the watch was produced in 1938. Great!

@Mercurial I will take the measurements and will keep you informed.

Thank you all. This forum is incredible 👍

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      Very interesting! I answered the mail from Longines, explaining that I was a bit disappointed and that I wouldn't ask for a costly confirmation for a watch which isn't a high-end one ... and I received another email explaining that they couldn't not certify the authenticity of the watch, but they could specify that, according to the serial number on the caliber and to their handwritten records, the watch was produced in 1938. Great! @Mercurial I will take the measurements and will keep you informed. Thank you all. This forum is incredible 👍
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      A quick Google for Longines 25.17 found several similar watches - like this one with writing on the case back similar to yours https://benjaminmarcello.nl/product/longines-cal-25-17-tank-from-1938/
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