This Vacheron Constantin Patrimony Perpetual Calendar Ultra-Thin reference 43175/000G-9874 was made in a run of 30 pieces, a brief edition within one of the brand's most restrained modern lines. That scarcity sits against a complication Vacheron Constantin has long handled with unusual elegance, giving the watch a stronger claim on a collector's attention than the quiet Patrimony case first suggests. Its automatic movement carries a perpetual calendar with moonphase, which is exactly the sort of high complication that benefits from the line's disciplined layout. In 18k white gold, the case measures 41mm across and 9mm thick, keeping the watch notably slim for what it contains. The black dial shifts the Patrimony's usual tone toward something cooler and more formal, while preserving the balance that makes this configuration work. For anyone building around modern perpetual calendars rather than simply accumulating them, the appeal here is how much horology Vacheron fit into so little watch.