Arnold & Son Perpetual Moon Obsidian

The Arnold & Son Perpetual Moon Obsidian is a new addition to the brand’s popular Perpetual Moon collection. Its dial is formed of golden obsidian, a volcanic stone from Central America and its 42mm case is presented in 18-carat red gold. The model is limited to just 28 timepieces, granting a notable degree of exclusivity.

Arnold & Son Perpetual Moon Obsidian

John Arnold (1736-1799), a son of Cornwall, England is a name that will be familiar to all horophiles with a penchant for history. Along with John Harrison and other watchmakers of the period, Arnold was eager to win a prize from the Board of Longitude. By inventing a device to solve the problem of finding the longitude at sea, a watchmaker could receive a substantial sum of money. In 1780, the Board of Longitude recognised Arnold’s chronometer No.2, declaring it superior to any watch produced previously.

Marine chronometers would remain an obsession of John Arnold until he passed away in 1799. However, John Arnold did not focus on marine chronometers alone. He produced the first watch equipped with a jewelled ruby cylinder escapement. Other firsts included a small half-quarter repeating watch set in a ring, a detent escapement and a helical balance spring.

Abraham-Louis Breguet (1747-1823), arguably the greatest watchmaker of all time, modified one of Arnold’s pocket chronometers, fitting it with the first tourbillon escapement ever designed. This watch is now part of the British Museum’s collection. Arnold and Breguet were close friends for many years. After John Arnold’s death, Breguet presented Arnold’s son with the aforementioned tourbillon (1808).

The brand Arnold & Son was relaunched in 1995 and subsequently became a fully integrated Manufacture in 2010. Its incredible in-house expertise allows the company to make remarkable watches with optimally-placed indications. This is made possible because the dial is always conceived first and the movement is developed thereafter, the polar opposite of the standard approach.

Arnold & Son Perpetual Moon Obsidian

The Perpetual Moon features one of the biggest moon phase apertures on the market and, with only one day’s deviation over 122 years, its lunar-themed complication is incredibly accurate. Should the moon phase require adjustment, changes can be made using a stylus in conjunction with the caseband corrector. An additional moon phase indication is positioned to the rear of the watch which is used for setting purposes.

This paragon of fine watchmaking with its Haute Horlogerie finishing is housed in a 42mm case and has historically been offered in three dial variants, that is until now. The Maison from La Chaux-de-Fonds has just unveiled the Arnold & Son Perpetual Moon Obsidian. It shares much in common with its older siblings, save for its dial epidermis which is formed of golden obsidian, a volcanic stone from Central America. This latest model features an 18-carat red gold case and is limited to just 28 timepieces.

Price: Arnold & Son Perpetual Moon Obsidian – CHF 31,900 excluding tax

The brand’s press release

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.

Arnold & Son Perpetual Moon Obsidian


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.

A golden heart

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 Perpetual Moon Obsidian


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.

Arnold & Son Perpetual Moon Obsidian


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.

Further reading

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