Bi-color gold Wrist Chronometer no. 5497

Case: s/n; 10194, 18k white gold, with 18k yellow gold 'keyhole' dial cover Dial: silver dial, with jump hour display, seconds disk and simple seconds, dial signed Cartier Movement: 10''' tonneau, 8 adj, 18 jewels, 2 x Poincon de Geneva quality seals, obtained at November 23, 1928 Provenance: 1928 - Niton, Geneva 1928 - Cartier, Paris (very unlikely !, Please read below) 1994 - Antiquorum 2020 - Italian collector 2022 - new owner unknown White Cartier Bianco' by Osvaldo Patrizzi's, Antiquorum, page 150-151/ photo’s by Philip Poniz; 18k white gold, yellow gold 'key hole' dial, jump hour, min disk and sec. The same Cartier jumping hour is shown at Antiquorum, but without the gold 'keyhole' dial cover. Antiquorum, Auction No. 127, April 10, 1994, Lot No. 171, Geneva, Hotel des Bergues 22-25,000 CHF" Cartier Paris, made by Niton Geneva, 1930' Very fine and rare "tortue", jumping-hour, 18ct white gold gentleman's wristwatch. C. massive, polished, satined, dedicated back. D. satined silver with painted Arabic numerals for the minutes and the seconds, aperture for the jumpinghours. "Flèche" blued steel hands. M. 9"' tonneau, rhodiumed, "fausses côtes" decoration, 18 jewels, lever escapement, cut bimetallic balance with all ajustments, Breguet balance-spring. Dial, case and movement signed. In very good condition. Dim. 25 x 35 mm. C. massive, polished, satined, dedicated back. D. satined silver with painted Arabic numerals for the minutes and the seconds, aperture for the jumpinghours. "Flèche" blued steel hands. " According to the former auctioneer, the Cartier register shows that Cartier No 28343 was completed in 1932 and had bought the movement from Niton. Interesting findings/notes ! Cartier bought at least 4 jump hour wristwatches by Niton, all in a tank shape case. The one we know is numbered with Cartier's serial numbers on the case back inside (see also the other Cartier jump hour wristwatches in this online Niton database). It is interesting that this tonneau shaped jumping hour wristwatch only shows Niton serial numbers. There are No Cartier serial numbers on the case back or case back inside. Also interesting is the fact that this tonneau shaped movement by Niton with serial number 5497 obtained 2 x Poincon de Geneva quality seals on November 23, 1928. This date is (less) earlier than "Cartier's first jump hour wristwatch ever", the so called "Cartier Paris Tank à Guichet" which was sold to Sir Bhupindra Singh, Maharaja of Patialato. The Marahaja Bhupinder Sing gave Cartier order to develop the "Tank a Guichet" on October 31 and was finished one month later on November 30, 1928. Further, according to some insiders there is an interesting story behind this watch too; "before submitting for the first auction (when it appeared for the first time in public), the 18k gold key hole cover was removed to show the "Cartier" signature, which was added later. Also much later the original 18k gold key hole cover was replaced again". So it is very uncertain that Niton produced this one too especially for Cartier. But, as your ask me, two things are certain. The watch is 100% by Niton and... has a very interesting background story.