Help me identify Cartier Jump hour EWC 1920s watch

Greetings,

I am looking for a Cartier connoisseur's advice. Just recently, I added to my collection a rare Cartier Jump Hour watch.

After the first impressions, it seems to be a pebble-style/golfer pocket watch. No bow, hinges, holes, anything. Just a smooth and slick design, knife edges, and a recessed winding crown. Very unusual features. Ahead of its period.

There are approximately. 10 Cartier pocket watches with jump-hour complications.

This is, based on my observation, the list of oddities and key differentiators:

• The dial ( mine has almost a full face covered with a guilloche pattern ), including the part with the numerals
• Aperture for the hour indicator got a unique, irregular shape
• The case has no hallmarks, a display case back, and is elaborately made in a very high quality
• The serial number is very close to some examples of Jump hour pocket watches made from platinum
• It has no dual number sequence, nor the Cartier inventory number presented elsewhere

Now, the major open questions part

1. Cartier made very wild and unique designs in the 1920s and 1930s; some watches got a display / transparent case. Did Cartier ever produce a pebble-style or golfer-style pocket watch, respectively?
2. May this specimen be a prototype?
3. Could this eventually be part of something bigger, and now is missing parts (e.g., stand, outer shell, case, whatever)?

The watch comes from an elderly French gentleman who doesn't know much about it and wasn't into watches at all.

Your expert advice and knowledge shared is much appreciated!

A nice weekend to all,

Luke

is there any chance to take off the dial

Absolutely! My watchmaker has it on his bench. I will update this thread soon.

I the meantime, some intriguing facts about the Cartier pocket watches from the era.

The most fascinating part to me is the dial: 0.2mm thick, clips on the movement and the guilloche pattern is stamped not hand-engraved. Sick!

https://www.thenakedwatchmaker.com/new-page-2

I have found some genuine Cartier watches from the 1920s and 1930s encapsulated in the same case type.

https://www.sothebys.com/en/auctions/ecatalogue/2004/magnificent-jewels-n08034/lot.184.html