Jaquet Droz Grande Seconde Moon

In 2017, Jaquet Droz gave its principal watch design, the Grande Seconde, one of the most popular complications of the year, the moon phase display in the Grande Seconde Moon. It is a so-called astronomical moon phase, exact to one day’s discrepancy every 122 years. By way of comparison, the traditional mechanism based on a 59-tooth wheel – approximating the lunar month to 29.5 days – accumulates an error of one day in about two and a half years. The watch is made in three versions, of which the most attractive (in my opinion) is the red gold version with ivory dial.

The lower dial shows the seconds, the date, and the moon phase, with a disc in blued steel on which there are a number of tiny gold stars. The moon phase is adjusted by means of a corrector at 8 o’clock using the stylus provided with the watch.

Usually a moon phase is the classic women’s complication, but in this piece, the case is 43 mm in diameter and so definitely for men. It is 13.23 mm thick, and has the standard water resistance of 3 bar (nothing more than splashes and rain). Each watch has its serial number engraved on the case-back. The strap is in brown alligator with a red gold buckle.

Self-winding movement

The watch is powered by the Jaquet Droz 2660QL3 self-winding mechanical movement, providing 68 hours’ power reserve by means of the double mainspring barrels. Balance spring and pallet horns are in silicon, and the balance runs at 4 Hertz. The red gold oscillating weight can be viewed through the sapphire caseback.