Longines 35mm Tre Tacche Cal. 12.68 Z ID & Dating Help

W

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willing2learn

·Jun 10, 2026

Hello everyone,

I would appreciate some help identifying and dating this Longines.

Known details:

• 35 mm diameter excluding crown
• Manual-wind movement
• Small seconds
• Movement serial number: 6,234,559
• Case reference: 21692
• Additional case number: 149
• Three-notch screw-back case

I have owned this watch for many years and know its provenance well enough that I have no reason to suspect a recase or marriage, but I would like to learn more about the watch itself.

My main questions are:

1. What is the movement caliber?
2. Approximately when was the watch produced based on the serial number?
3. Does the dial, handset, crown and case appear correct for the period?
4. Is there any information available on case reference 21692?
5. Is the three-notch screw-back case typical for Longines of this era?
6. Would a 35 mm case have been considered oversized for the period, and how uncommon would that size have been?

I have attached photographs of the dial, movement, case, case back and movement serial number.

Many thanks for any information or observations.

 

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Radiumpassion

·Jun 10, 2026

Many of your questioms you will find by Google , but looks like a nice original tre tacche
with 12.68 Z movement.

 

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willing2learn

·Jun 10, 2026

Radiumpassion

Many of your questioms you will find by Google , but looks like a nice original tre tacche
with 12.68 Z movement.

Thanks for your reply however google and the AI told me to come here for more answers 😀

 

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Mark020

·Jun 10, 2026·not the sharpest pencil in the ΩF drawer

W willing2learn

Approximately when was the watch produced based on the serial number

Send Longines a mail with your pictures and the will tell you - free of charge - the day it was sold and where ;-)

But 6.23m will be end 1941, early 1942 I assume.

Most info on these type of cases can be found by searching for 'tre tacche'. I'd say that the watch is all correct

 

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willing2learn

·Jun 10, 2026

Mark020

Send Longines a mail with your pictures and the will tell you - free of charge - the day it was sold and where ;-)

But 6.23m will be end 1941, early 1942 I assume.

Most info on these type of cases can be found by searching for 'tre tacche'. I'd say that the watch is all correct

Thank you for the reassurance, do you think a extract from the archives at Longines is worth it for this watch?

 

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Mark020

·Jun 10, 2026·not the sharpest pencil in the ΩF drawer

The mail is free. If you want the same info on paper you pay for it

 

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bardamu

·Jun 13, 2026

Mark020

The mail is free. If you want the same info on paper you pay for it

They didn't tell me anything for free, not even the date of invoice.

 

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Mark020

·Jun 13, 2026·not the sharpest pencil in the ΩF drawer

I've never paid for it and did it 5 times or so

 

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AHW

·Jun 16, 2026

Mark020

I've never paid for it and did it 5 times or so

I contacted Longines Heritage recently for an extract and they told me it has changed. They only confirmed that my watch was a chronograph, date, and original sales location. You now have to pay for the specific information.

They were still extremely helpful and responsive though even without paying for the full extract.

 

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Dan S

·Jun 16, 2026

Mark020

I've never paid for it and did it 5 times or so

It's not free any more, unfortunately. The policy changed. Very sad.

 

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hugh162

·Jun 26, 2026

I was able to get free archive information very recently by emailing the heritage team (not the physical extract, just the info via email).