una Magna features Arnold & Son’s first three-dimensional moon. With this original timepiece, the Swiss watchmaker with English roots aims to make a lasting impression by presenting the largest moon ever created in relief for a wristwatch. Beneath an off-centred dial at 12 o’clock, which constitutes one of the house’s aesthetic signatures, Arnold & Son has placed a rotating sphere that accurately represents the appearance of the quarters of the moon against a starry backdrop that is more dazzling than a midsummer night sky.

Presented in a 44 mm red-gold case, Arnold & Son has recreated one of its distinctive designs. The off-centred hours and minutes dial at 12 o’clock frees up substantial space for displaying complications, such as this spherical moon measuring 12 mm in diameter. Its size is not its only distinctive feature. Half of the moon is made of marble to represent the illuminated part of the Earth’s satellite, while the other half is made of aventurine glass to depict the darker side. Neither material has ever been used in a three-dimensional design such as this. Changing from dazzling white to a deep, starry blue, the Luna Magna’s quarters have been delicately depicted to replicate the appearance of the lunar disc.

The large moon emerges from the main plate of the A&S1021 calibre without upsetting the overall balance of the timepiece. Arnold & Son has drawn on its remarkable creativity to make Luna Magna a well-proportioned watch that showcases the incredible volume of its moon.

The lunar globe thus appears halfway up the movement, perfectly positioned between the top and bottom. The upper part is encased in a glass box. This technique has been repeated on the case-back side, where the sapphire crystal rests on the wrist. By placing most of the volume in these sapphire crystals, the Luna Magna’s case has a total height of 15.9 mm. Lastly, to bring the overall piece together, the deeply tapered lugs extend the curvature of the sapphire crystal to meet the natural curve of the wrist.

Arnold & Son has an ancient, long-standing relationship with the phases of the moon. Guided by the life of John Arnold and the mark he made in the Royal Navy during the 18th century, the house has frequently endeavoured to depict the age of this satellite as accurately and as beautifully as possible. By completely reinventing the way the Earth’s satellite is depicted, Luna Magna elevates itself by pushing the boundaries of this astronomical and poetic watchmaking exercise.

Luna Magna is driven by the A&S1021 calibre, which has been fully developed, manufactured, assembled and adjusted in the Manufacture. This new hand-wound calibre, which has been designed with the lunar globe in mind, features a 90-hour power reserve and a regulating organ oscillating at a frequency of 3 Hz. The movement also includes a secondary display detailing the age of the moon on the case-back side. Its clearly readable markings are designed for high-precision adjustments.

The sophisticated celestial mechanics are also based on precise astronomical reality. In fact, the duration of a complete lunar cycle is 29 days, 12 hours, 44 minutes and 2.8 seconds. Arnold & Son has managed to replicate it in such a way that it will take 122 years for the movement’s display to deviate from the correct celestial reading by one day. The correction required at this time will be easy to dispense, as the Luna Magna’s moon-phase function can be accessed directly by the crown. This practical feature has been made possible by Arnold & Son’s total mastery of the watchmaking process.

Technical specifications

• Functions hours, minutes, astronomical three-dimensional moon phases (one-day correction required every 122 years), moon-phase indicator on the back

• Movement Calibre A&S1021, hand-wound mechanical Jewels 35 Diameter 37.60 mm Thickness 12.00 mm with three-dimensional moon (4.75 mm without moon) Power reserve 90 hours Frequency 3 Hz / 21,600 vph Finishes main plate: circular-grained bridges: chamfered, with Côtes de Genève stripes radiating from the centre wheels: circular satin-finished screws: blued and chamfered, polished heads moon-phase indicator: circular satin-finished

• Dial aventurine glass white lacquered hours dial blue PVD flange

• Moon 12.00 mm in diameter white marble half sphere and aventurine glass half sphere

• Case Material 18-carat red gold (5N) Diameter 44.00 mm Thickness 15.90 mm (with crystal) Crystal domed sapphire with an anti-reflective coating on both sides Case back sapphire crystal with an anti-reflective coating on the inside Water-resistance 30 metres / 100 feet

• Strap Material hand-stitched blue alligator leather Buckle pin buckle in 18-carat red gold (5N)

• Reference 1LMAR.A02A.C153A

• Limited edition 28 timepieces

• Global retail price CHF 43,900 excl. tax (may be subject to modifications)