Most moon-phase displays typically require the use of loupe to be fully appreciated, but no such instrument is needed when it comes to Arnold & Son’s latest watch. Instead, it provides us with a permanent telescopic view of the moon on a spectacular guilloche dial. Part of the Royal Collection, the new timepiece is an evolution of the HM Perpetual Moon, a 2013 release that introduced one of the largest moon phases on the market at 11.20 mm (and which we covered at Basel when it launched).
As it name suggests, the HM Double Hemisphere Perpetual Moon doubles the fun with a second moon phase sitting directly opposite the original, between 4 and 8 o’clock. Together, they display the cycle of our favorite satellite, as it is seen from both the Northern and the Southern Hemisphere.
Intuitively, the Northern Hemisphere occupies the top of the dial, running from 10 o’clock to 2 o’clock, while the Southern Hemisphere occupies the bottom. A small world map at 3 o’clock, cleverly placed so that its equator line cuts the dial in two equal halves, eliminates any possible confusion, with arrows on both side pointing which way is up.
The stunning guilloche moon disc of the HM Perpetual Moon is back, powered once again by the hand-wound caliber A&S1512 made by the Arnold & Son manufacture. And again, as in the HM Perpetual Moon, it rotates underneath a guilloche dial, adding a sense of depth to the watch.
However, once black, it now comes in a more romantic translucent blue lacquer, with golden stars and stylized constellations on either side, fully displayed thanks to a new opening on the bottom half of the watch.
The new moon disc and dial are nicely complemented by an 18-karat red-gold case, measuring 42 mm. Themselves made in gold, the moons measure 11.2 mm each and are casts of the original hand-sculpted model used in the HM Perpetual Moon.
A third moon display, visible via a transparent case back, displays the eight key stages during its revolution around the earth for more exact setting. Accurate to one day every 122 years, the moon phase can be reset easily with a single push on the corrector at 2:00.
What makes this moon-phase remarkable, besides the ridiculous size of its moons, is the lack of other complications on the dial. Usually relegated to a subsidiary dial and given the supporting role, the moon stars in this timepiece.
While its spectacular ballet plays out on the dial side, a sapphire case back offers a complete view of the movement, including its manually chamfered bridges with polished edges, fine circular graining finish, and Cotes de Geneve stripes.
Caliber A&S1512 features two barrels that provide the watch with 90 hours of power reserve. The watch is water resistant to 30 meters.
The Arnold & Son HM Double Hemisphere Perpetual Moon comes with a brown or black alligator strap, and is priced at $30,500. Visit them online here.
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