Two of watchmaking's most demanding mechanisms in one 40mm white gold case: a split-seconds chronograph, which times two events at once by holding one hand while the other runs, and a perpetual calendar. The split-seconds half is the harder one — the isolating clamp that arrests one hand without disturbing the other is among the most delicate assemblies in a wristwatch, and it is unforgiving of mis-operation. What matters on examination: that the rattrapante hands return to exact superimposition after a split; that the chronograph resets cleanly to zero; and that the piece has not been used as a stopwatch by an owner unaware of the mechanism's tolerances. Calendar function and set completeness are confirmed through the desk. Maker: Patek Philippe. Reference: 5204G-010. Available through ELITA's private desk — verification review, discreet handling and storage. Price on request.