Hi Longines lovers Apologies if that question has already been addressed elsewhere. When browsing through vintage Longines I appreciate Longines' practice of stamping or engraving the matching case number on the case back as well as on one of the lugs. Great way to check and avoid Frankongines. Unfortunately, I noticed that Longines stopped that practice at some point, some time in the 60s? I'm interested in knowing when Longines started and stopped this practices. Also tried Dr. Google, but in vain. Many thanks for sharing your insights.
They stopped sometime in the early 50s i think, maybe it differ from model to model but all I have owned that are stamped have been from the 40s!
I had a 1957 Conquest (based on the Extract) with matching 3-digit numbers on the back of a lug and inside the case-back.
Based on what I have seen, this practice began around 1936 with the introduction of the waterproof "tre tacche" (e.g. reference 3777) and continued to be used into the mid-1960s on at least some waterproof references (e.g. 902x).
I’ve only seen it on screw back cases, I suspect it’s because the snap backs are easier to fit while the screw backs have to be really tight and precise.
Many thanks everyone for sharing. Learnt something again today . Funny enough, it was on the 9022 currently for sale in the sales forum, where I noticed the missing number on the lug and started wondering. But the 9024 also for sale here still has it, though the serial number is higher. Interesting.
I have a steel pocketwatch with a non hinged caseback and matching number on caseback and case. Maybe it was the procedure of a specific case maker?
I don’t think so because it’s the second number on the back after the order number. To me it clearly seems applied at the same time or in the same framework as the Longines batch system.