Arnold & Son has mastered many high complications but has become particularly lauded for its striking, photorealistic moon-phase displays, the most recent showcased in last year’s Perpetual Moon Obsidian. This year, at Watches & Wonders, the Swiss manufacture named for 18th Century British horologist John Arnold elevated its lunar savoir faire to a new, record-setting level with the Luna Magna, which boasts the largest 3D moon ever built into a wristwatch.
The spherical moon that dominates the lower dial of the Luna Magna combines one hemisphere of marble, for the light side of the moon, and the other of aventurine glass, for the dark side; neither material has ever been used to create a 3D moon for a watch. It measures a substantial 12 mm in diameter and floats inside an aventurine dial that depicts a star-filled midsummer sky. How does this voluminous lunar globe fit within the relatively modest dimensions of a luxury timepiece? It is positioned perfectly between the top and bottom of the movement, with its upper part enclosed in a domed section of the sapphire crystal; the design is repeated on the lower side of the watch, in which another sapphire glass rests in the small of the wrist. Measuring from one sapphire dome to the other, the case’s total thickness is only 15.9 mm.
Above the gigantic moon-phase is an off-centered, white-lacquered subdial on which the current hour and minute are displayed by blued hands on Roman numeral markers. The round, polished case, 44 mm in diameter and made of 18k rose gold, contains hand-wound Caliber A&S1021, which has been fully developed, manufactured, assembled and adjusted in-house at Arnold & Son’s manufacture in La Chaux-de-Fonds, Switzerland. Aside from its 3-Hz frequency, its impressive 90-hour power reserve, elaborate haute horlogerie finishes, the movement is distinguished by a special indicator for the age of the moon on its rear side. The latter device works in concert with the sophisticated moon-phase function, which is engineered to replicate the precise, real-life lunar cycle of 29 days, 12 hours, 44 minutes and 2.8 seconds and thus would not need adjustment for 122 years. The movement even makes such an adjustment easy, as the moon-phase settings can be accessed directly through the watch’s crown.
The Arnold & Son Luna Magna is mounted on a hand-stitched blue alligator strap, which fastens via a classic pin buckle in 18k rose gold. The strap connects to the watch through case’s deeply tapered lugs, which extend the curvature of the sapphire crystal and follow the natural contours of the wrist. Strictly limited to 28 pieces, it will be priced at $50,500.