ith its XXL moon, the Perpetual Moon is ruled by Selene, the goddess of this celestial body. Arnold & Son presents a limited edition of 28 pieces featuring this distinctive complication, adorned with an extraordinary material rarely seen in watchmaking. With a dial made from Mexican obsidian, this timepiece appears to be bathed in bronze moonlight. The stone is reflected in the large rhodium-plated moon and the perfectly polished hour-markers. The result is an interplay of reflections, vibrations and warmth that echoes the light of Earth’s satellite.

Showcasing one of the largest moons to be found in the watchmaking sphere, the Arnold & Son Perpetual Moon Obsidian stands out for the size of its complication and the aesthetic approach employed by the resolutely British Swiss brand. Housed in a 42 mm red gold case, beneath a rarely seen golden obsidian dial, is its hand-wound calibre A&S1512, offering a precision double moon phase display.

On the movement side, a hand display allows for extremely fine adjustments. On the dial side, a large moon disc occupies almost the entire aperture, presented in a vast window with a round cut-out that allows the changing faces of the moon to be admired. The realistic depiction is crossed by shadows and areas of relief to add to its presence.

In the exterior details, Arnold & Son has taken this approach even further. The moon is only visible because it reflects the light from the sun. In the same way, the light brings the Perpetual Moon Obsidian to life with its shimmering reflections.

From Mexico, the Manufacture sourced of one of the oldest and most intriguing stones: golden obsidian. This volcanic stone has been mined in Central America since time immemorial and was used in particular in the religious ceremonies of pre-Columbian civilisations. Obsidian has a very high silica content, making it a hard and shiny material. Golden obsidian owes its shimmer to the semi-precious stone’s chemical composition and its specific crystallisation. Its bronze hue extends far beneath the surface, right into the heart of the material. Despite the minute amount used for the dial, it still produces a glistening effect, reflected in turn in the hands and hour-markers.

Arnold & Son selected cool shades to contrast with the stone. The moon and hands are rhodium-plated and the hour-markers are made from diamond-polished white gold. Together, these choices enhance the reflections of the golden obsidian and the red gold of the case. To complete this contrasting interplay of warm and cool tones, the brand chose a blue alligator-leather strap with visible silver-coloured topstitching.

Like all the movements used by Arnold & Son, the calibre A&S1512 was entirely developed, produced, decorated, assembled, adjusted and cased up in the brand’s manufacture in La Chaux-de-Fonds. This calibre is based on a large barrel with an oscillation frequency of 3 Hz, giving a 90-hour power reserve. Last but not least, the moon phase display of this movement will remain accurate for 122 years before deviating from the actual lunar cycle by one day.

Price: CHF 31,900