Longines rare 15cal auction in hk... but suspicious..

Not many people are going to be able to help you without an English translation of that website.
gatorcpa

For posterity:



Lot Essay

A completely breathtaking large-size vintage Longines single-button chronograph. Its large 39.5 mm. diameter, sensational two-tone dial and superb looks make this amazing timepiece one of the ultimate specimens among all vintage Longines chronographs.

The ravishing silvered and rose two-tone dial is complex yet perfectly proportioned, with blue outer telemeter scale used for measuring distances based upon an visible and audible event, for example during a thunderstorm. The divisions on the scale are based on the speed of sound in air (340 meters per second). In the centre is a blue spiral tachymeter scale for measuring distance over speed. Subsidiary dials for 30-minute register at 3 o’clock and seconds at 9 o’clock provide visual symmetry.

According to the Archives of Montres Longines Francillon SA, the present watch was sold to Italy in 1935.

Condition Report

Movement: operating, service needed
Dial: with spotting and surface scratches consistent to its age
Case: with surface scratches, tiny pinhead dings and minor knife marks to the side of case from opening, signs of light oxidation near lugs and to the edge of the bezel, hallmarks inside the case back remain sharp
Crystal: with minor scratches
Strap: brown associated leather strap is in new condition
Overall condition: good for its age

Thank you.

I recognize this example. Photos of it have been on the web for a number of years. A coupe of things that I notice: both the hour and minute hands have blunt ends, and the presence of "Swiss Made" strikes me as a bit odd. The printing and fonts look very good. Below is a comparison with a 13ZN that was invoiced 27 October 1937 to Perret (Brazil). This is not a perfect comparison as the dials differ in a number of ways. However, the signatures appear to be very similar. Further below is a comparison with another 13ZN that was invoiced 30 September 1937 to Ostersetzer (Italy). This dial has a similar design, barring the sub-dials and arrangement of "Anti-magnetique". I notice that some of the printing on the Valjoux example is incomplete, e.g., "30" of minute scale, and the second "E" in "Telemetre". The dial also appears a bit washed out, though the photos might not be helping. Maybe it has been cleaned?

Source: https://benjaminmarcello.nl/product/longines-13zn-monopusher-chronograph-1937/


Source: https://www.monacolegendauctions.com/auction/exclusive-timepieces-15/lot-72

P. S. Here is a neat Zenith that has a Valjoux 22GH and a dial with some similar traits: https://omegaforums.net/threads/rare-ug-zenith-compur.165475/#post-2260882.