Ultrathin Tourbillon Onyx Edition

Mystical, untamed and dazzling, the Perpetual Moon 41.5 Red Gold “Year of the Horse” follows in the footsteps of Arnold & Son’s Chinese zodiac collections. In the year spanning 2026 and 2027, the Fire Horse will set the astrological tone for connoisseurs of watchmaking and métiers d’art. To celebrate this flamboyant sign, Arnold & Son presents a limited edition of eight pieces, housed in 41.5-mm red gold cases. And while the noble animal is ever alert, it is at night that the full extent of its fiery, mysterious and incandescent nature is revealed.

A horse rears on a hill top – a commanding silhouette carved out against a star-studded sky, surrounded by the sparks of a metaphorical fire. This is Arnold & Son’s interpretation of the Fire Horse, the sign that will succeed the Wood Snake on 17 February 2026. For the sixth consecutive year, Arnold & Son is back in the saddle, drawing on the full breadth of its artistic savoir-faire. Miniature painting, three-dimensional engraving, fine stonework and the refined finishing of an astronomical moon-phase calibre: the Perpetual Moon 41.5 Red Gold “Year of the Horse” tells a tale of excellence, symbolism and vital energy.

An ardent design
Behind the expressive power of the scene, lies all of Arnold & Son’s creativity and mastery. The horse, in 18-carat red gold appliqué, is hand engraved. From hooves to mane, every muscle seems to ripple with energy. The black aventurine sky shimmers like a vast, celestial expanse, where distant stars mingle with mountainous reliefs and shadowy woodland undergrowth.

In the horse’s wake, hand-painted golden dust evokes a trail of sparks that ignite one after the other as the animal passes. These glowing flashes reflect its inner fire and untamed spirit. Touches of red and yellow Super-LumiNova, diffusing the same nocturnal shades, transform the scene as the light dims. Under the radiant mother-of-pearl moon, the horse’s majestic silhouette stands out, while the embers smoulder with new intensity. Not far away, the constellations of Cassiopeia and Ursa Major take shape on the lunar disc, completing this dual-faced, dual-display dial.

A noble pedigree
On the case back, a secondary moon-phase display enables fast, accurate setting of the lunar age. The heart of the Perpetual Moon 41.5 Red Gold “Year of the Horse”, the manual winding A&S1512 calibre, follows the lunar cycle with exceptional precision. While a true lunation lasts 29 days, 12 hours, 44 minutes and 2.8 seconds, Arnold & Son have achieved such precision that it would take 122 years for the display to drift by a single day from the actual lunar cycle, provided the watch is kept fully wound.

As for all Arnold & Son movements, the A&S1512 calibre is developed, manufactured, decorated, assembled, adjusted and cased up at the Chaux-de-Fonds manufacture. Equipped with two barrels and beating at 3 Hz, it gives the Perpetual Moon 41.5 Red Gold “Year of the Horse” a generous power reserve of 90 hours.

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Arnold & Son presents two new evocative versions of its ultra-thin HM model, featuring dials crafted from Namibian pietersite. Often called the "stone of storms," this decorative mineral belongs to the chalcedony family and was first discovered by Sid Pieters in the early 1960s. Each unique dial displays delicate, swirling patterns that recall the turbulent skies and foaming waves of Cornwall, the English birthplace of founder John Arnold. This design pays tribute to the ingenuity of the legendary watchmaker while celebrating the spirit of those who maintain their course in a challenging world.

The designation "HM" was intentionally chosen to reflect the watch's focus on displaying only hours and minutes, while simultaneously serving as a historical nod to the British Royal Navy. In naval tradition, HM stands for "His or Her Majesty’s," a title that appeared in the 17th century and was later formalized as HMS. By transposing this reference to watchmaking, Arnold & Son connects the precision of modern horology with England's maritime history, specifically the era when John Arnold’s marine chronometers enabled the exploration of new lands.

Encased in a choice of 18-carat red gold or stainless steel, the HM Pietersite is a masterpiece of elegance and restraint. The case measures a refined 39.5 mm in diameter with a remarkably slim profile of just 7.82 mm. To complement the dreamlike, diaphanous patterns of the pietersite dial, the timepiece is paired with a matte ink-blue alligator leather strap and a traditional pin buckle crafted from the same metal as the case. These limited editions are produced in extremely small quantities, with only 8 pieces available in red gold and 18 in steel.

At the heart of this timepiece lies the ultra-thin, in-house A&S1001 manual-winding calibre. Visible through a sapphire crystal case back, the movement is a showcase of luxury finishing, featuring a rhodium-plated main plate with circular graining and bridges adorned with radiating Côtes de Genève. Despite its slender height of only 2.70 mm, the movement offers exceptional performance with a generous 90-hour power reserve. Every detail, from the snail-finished wheels to the blued screws with polished heads, reflects the most exacting standards of Swiss watchmaking.

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