Here we have a very attractive silver-cased pocket watch attributed to Vacheron & Constantin circa 1900, as offered on a well-known internet auction site. The style, particularily the hands and heavily engraved case, shout that it was manufactured for the German market.
Examination of the hallmarks confirms this theory, as both Swiss and German (crescent/crown) markings are present. This was the practice to ease entry across the border.
The case and movement number were submitted to the Heritage Department who, in their usual wonderful manner, confirm a legitimate marriage in 1903. However, the records are silent on this movement having achieved a chronometer rating.
The style of the engraved "Chronometre" is unusal for V&C with the elongated R and there is even a hint that the accent on the E of Geneve is at a different angle. I'm now suspecting that "Chronometre" was a later addition to the cuvette. This may still be a legitmate exercise if the watch was submitted for independent testing by the retailer which was uncommon but not unknown.
The movement is clean but not what I would expect of a chronometer-grade movement from V&C. Quite ordinary, actually, but with careful adjustment it might just pass a 45 day observatory test with a lower score. Verifying it's chronometre rating is essential given the questions arising.
With the French spelling of "Chronometre", the obvious source to check for independent testing is the Geneva Observatory and, after a week or so, they respond that their records to not identify this movement number. Some research into German chronometer testing of that period reveals the only facility was the Norddeutsche Seewarte in Hamburg, which was devoted to marine chronometers.
The seller indicates the watch is from an estate and has no information except to reassure that it came from a collector. While there is no definative smoking-gun, I'm not willing to risk purchasing this watch. As attractive as it may be, it just doesn't feel right!