The 13ZN is one of collectors’ favorite calibers from Longines and rightly so. The Longines 3756 13ZN movement, circa 1936, was truly innovative and beautiful. It featured an ‘in house’ (before it was cool) movement, one of the first ever chronograph complications in a wristwatch (argued, intentionally left vague), 17 jewels, a 18000 VPH beat, a flyback, and Breguet hairspring. They were produced in mass quantities from 1936 until well after the second world war. The flyback mechanism was pioneered here by Longines in order to allow aviators to reset while the chronograph was running. It was often necessary for navigation in those mechanical times to time, change direction, time, change direction, time fire for a period of time, change direction, etc. Although some were toothed to prevent this, the vast majority of 13ZN movements were flybacks. Something nonexistent from other manufacturers of the time until the Breguet XX.
Many variations on materials, crowns, chronograph pushers, and dials exist in the 13ZN; that’s a part of what makes them so fun to hunt. Cases even range from 34 to 40mm. Another reason for their popularity is that many of Longines production records remained intact through both wars. It is quite common to be able to contact Longines and find information on production and the original owner based on your watch’s serial number. Many even come with engraved double case backs like a pocket watch of the time might (not here). Prices for original pieces have been on a slightly parabolic increase since the early 2000s, to no surprise.
Now to the bad news. The 13ZN is often faked or otherwise adulterated. Redials sell amok. Re-cases as well. Because the 13ZN was based off of Longines earlier pocket watch 13.33Z, you may see reworked pocket watches. Serial numbers and loupe investigations become very important in this space. Luckily, this piece comes to us via Mentawatches. I have not yet seen a disreputable piece leave their hands and this example appears no different. The fonts all appear correct, they note that the hands have been touched but will include originals, provided are open pictures of the serial for your investigation, and a note from Longines as to its provenance. Dial feet are also copper, not silver. All promising to be sure. Prices for sandwich dialed 13ZNs have ranged generally from 15000 to 40000 over the last five years. Unless you’re after the hour-register 13ZN, this is pretty near as good as it gets. A sure-fire success to any future collector.
Find this example here at a fair 26500.