The new Royal HM Perpetual Moon from Arnold & Son (ref. 1GLAR.I01A.C122A) certainly has one of the biggest moon phases display on the market.
The 42 mm red gold case houses the exclusive Arnold & Son mechanical hand-wound movement, the calibre A&S1512. This calibre was especially developed for this model with the objective of offering a uniquely precise moonphase. The calibre is also equipped with a double barrel to yield 90 hours of power reserve.
The HM Perpetual Moon offers one of the most accurate moon phases on the market, with only one day’s deviation every 122 years – at which point a single push on the corrector will keep it in sync for another 122 years.
Surprisingly, a second moon indication is installed at the back of the movement. This second moon display, visible via the transparent case back, features a graduated dial and a pointer hand that makes the setting very easy.
The movement features hand finishing of the highest standard, including manually chamfered bridges with polished edges, Côtes de Genève rayonnantes and fine circular graining, circular grained wheels, and blued screws with polished and chamfered edges.