By Samantha Walsh
In a testament to their tradition of watches with astronomical indications, Arnold & Son added another moon phase to the Royal Collection with a new version of the HM Perpetual Moon. In a steel case with a blue guilloche dial, the new HM Perpetual Moon features one of the largest moon phase apertures on the market.
The 29mm moon phase disc, which spreads from 10 to 2 o’clock, features a 11.2mm three-dimensional sculptured moon that was first hand-engraved and then duplicated for the series. The watch also has a unique easy-to-set feature thanks to the ingenious addition of a second moon indication at the back of the movement. The second moon display, visible via transparent case back, features a graduated dial and a pointer hand that allows for a more exact setting.
The 42 mm HM Perpetual Moon houses an exclusive Arnold & Son mechanical hand-wound movement specially developed for this model in order to offer a large, precise, three-dimensional moon phase. The exclusive A&S 1512 hand-wound caliber is also equipped with a double barrel to yield 90 hours of power reserve. With only one day’s deviation every 122 years, the HM Perpetual moon is also one of the most accurate moon phases on the market. The entire rhodium treated nickel-silver movement features stunning hand finishing.
The rich blue guilloche dial sits in a classically elegant stainless steel case. Viewed from the side, the housing is stepped and tapers from top to bottom for a perfect fit. The HM Perpetual Moon sits on a hand-stitched alligator strap and retails for $17,200.
Main technical characteristics:
Caliber: A&S1512 –Exclusive Arnold & Son mechanical movement, hand-wound, big perpetual moon, 27 jewels, diameter 34 mm, thickness 5.35 mm, power reserve 90 h, two barrels, 21’600 vibrations/h
Functions: hours, minutes, big perpetual moon, diameter disc: 29 mm, diameter moon: 11.2 mm, second moonphase indication on the back for setting purposes
Movement Decorations: nickel-silver movement, rhodium treated with Haute Horlogerie finishing: manually chamfered bridges with polished edges, fine circular graining and Côtes de Genève rayonnantes, blued screws with polished and chamfered edges
Dial: translucent blue lacquered guilloché, translucent blue lacquered guilloché moon disc with silvered moon and stars; back dial: fine circular graining, rhodium treated, rendition of the 8 phases of the moon
Case: stainless steel, diameter 42 mm, cambered sapphire with anti-reflective coating on both sides, case back see-through sapphire, water-resistant to 30 m
Strap: hand-stitched black or brown alligator leather