Arnold & Son Ultrathin Tourbillon Onyx 5N Red Gold 750/1000

The radical elegance of ultra-thin design

With the Ultrathin Tourbillon Onyx in 5N 750/1000 red gold, Arnold & Son presents a contemporary and minimalist vision of haute horlogerie. Produced in a limited edition of just eight pieces, this creation combines the sophistication of an ultra-thin flying tourbillon with the magnetic depth of black onyx.

Its main dial, crafted from genuine polished onyx, offers a rare visual presence. Arnold & Son pushes the boundaries of hardstone craftsmanship even further here by introducing, for the first time in the watchmaking world, a matte satin finish on an onyx subdial. This subtle contrast between glossy black and matte black creates a particularly refined interplay of textures, reinforcing the watch’s graphic and contemporary character.

At 6 o’clock, the large circular aperture reveals the cage of the one-minute flying tourbillon, meticulously hand-beveled. Suspended in this deep black universe, it becomes the focal point of the piece, showcasing the full extent of the manufacture’s expertise.

This edition also pays homage to John Arnold, an 18th-century English master watchmaker and a key figure in marine chronometers. Renowned for his innovative approach to horological precision, he was one of the first to use pierced rubies to reduce friction in mechanical movements.
The 41.5 mm fluted case in 5N 750/1000 red gold houses the A&S8300 hand-wound in-house caliber. At just 2.97 mm thick, this movement ranks among the thinnest tourbillon calibers on the market. Visible through the sapphire caseback, it reveals the finishing touches of the finest watchmaking: sunburst Côtes de Genève, hand-polished bevels, blued screws, and a hand-engraved 3N 750/1000 yellow gold tourbillon bridge.

Thanks to several technical optimizations made to the regulating organ and the tourbillon cage, this timepiece boasts an impressive 100-hour power reserve—a remarkable feat for such a slim watch.
At once discreet, technical, and deeply expressive, the Ultrathin Tourbillon Onyx in 5N 750/1000 red gold embodies contemporary haute horlogerie, where aesthetic purity dialogues with mechanical excellence.