Ultrathin Tourbillon Platinum Onyx LTD 8

A Study in Depth, Elegance and Chronometry

At the crossroads of refined minimalism and high-precision watchmaking, Arnold & Son unveils the Ultrathin Tourbillon Platinum Onyx—a timepiece that transforms the flying tourbillon into an expression of depth, contrast, and understated power.

Housed in a 41.5mm case crafted from 950 platinum, this limited edition of 8 pieces embodies the Maison’s chronometric heritage with contemporary restraint. Its broad dial fully exploits the intense black of onyx, creating a dramatic stage for the regulating organ at 6 o’clock and allowing the beauty of the tourbillon to emerge with striking clarity.

Mechanical Refinement: The A&S8300 Calibre

At the heart of the Ultrathin Tourbillon Platinum Onyx beats the Calibre A&S8300, a manual-winding Manufacture movement developed by Arnold & Son. Measuring just 2.97mm thick, this ultra-thin calibre gives the watch its elegant profile while preserving the technical authority expected of a haute horlogerie creation.

Operating at a frequency of 3 Hz and offering a remarkable 100-hour power reserve, the A&S8300 calibre reflects the Maison’s pursuit of chronometric excellence. Visible through the sapphire crystal caseback, it reveals refined finishing including radiating Côtes de Genève, chamfering, snailing on the two-barrel ratchet wheels, and polished, blued, and chamfered screws.

The Flying Tourbillon: A Regulating Organ in Motion

Positioned at 6 o’clock, the large flying tourbillon becomes the visual and mechanical centre of the composition. Its delicate cage opens through the onyx dial, revealing the hand-bevelled architecture of a mechanism conceived to combine precision, lightness, and visual poetry.

Its symbolic details recall Arnold & Son’s maritime heritage: a stylised sextant evokes John Arnold’s role in advancing the calculation of longitude, while the anchor-shaped counterweight serves as a reference for reading the seconds as the cage completes its one-minute rotation.

A Dial of Black Onyx: Mystery and Contrast

The identity of the Ultrathin Tourbillon Platinum Onyx is expressed through the refined duality of its stone dial. The main dial is fashioned from a finely polished disc of genuine black onyx, selected for its intense, enigmatic depth and long-standing association with strength, power, and discernment.

The concave hours-and-minutes sub-dial is also crafted from black onyx, but treated with a matt satin finish—a first in watchmaking according to the Maison. This subtle contrast between polished and matt stone brings texture, depth, and architectural balance to the display, while reinforcing Arnold & Son’s expertise in the art of working with ornamental stones.