Arnold & Son introduces two new watches at Watches & Wonders 2026, the HM Pietersite, a time only dress watch centred on a natural pietersite stone dial with swirling patterns in blue, brown and grey, framed by rounded applied metal markers along the edge, and the Ultrathin Tourbillon Onyx Edition, a more minimal counterpart defined by a deep black onyx dial that places full focus on the flying tourbillon at six o’clock.

HM Pietersite

HM Pietersite in red gold

HM Pietersite in stainless steel

The HM Pietersite takes its name from the natural pietersite dial, a decorative stone discovered in the 1960s. Sourced from Namibia, pietersite is known for irregular, swirling patterns formed by natural mineral structures, with each dial showing a different mix of blue, brown, and grey tones.

To let the material stand out, the dial is kept deliberately simple with a minimal layout and applied markers. Notably, the markers are small rounded polished metal studs, with larger ones at the hours and smaller ones for the minutes. Rather than distracting from the pietersite, they act as subtle accents that add structure and texture to the dial. Naturally, the studs follow the color of the case, with the red gold version looking warmer and more pronounced.

Inside is the in-house Calibre A&S1001, a manual-winding ultra-thin movement measuring just 2.70mm in height, but still delivering a 90-hour power reserve. The movement is visible through a sapphire caseback and finished with a distinctive design: radiating Côtes de Genève on the bridges and polished bevels.

The watch comes in a moderately sized case measuring 39.5mm in diameter and 7.82mm thick, giving it a flat, understated presence on the wrist. It is limited to 8 pieces in red gold and 18 pieces in steel.

Movement: Cal. A&S1001, manual-winding, 21,600 vph, 90-hour power reserve
Functions: Hours, minutes
Case: 39.5mm x 7.82mm, 18k red gold or stainless steel
Dial: Natural Namibian pietersite
Strap: Ink blue alligator leather strap with matching pin buckle
Availability: Limited to 8 pieces in red gold and 18 pieces in steel
Water resistance: 30m
Price: CHF 27,100 (red gold), CHF 16,200 (steel)

Ultrathin Tourbillon Onyx Edition

Ultrathin Tourbillon Onyx Edition

The Ultrathin Tourbillon Onyx Edition introduces a diametrically opposite style to the watch above: minimal, dark, and defined by the depth of natural onyx, paired with a flying tourbillon rather than a time only display.

The dial is built around a broad disc of natural onyx, known for its deep black tone and minimal visual variation. The sub dial is also formed in onyx, set in a concave profile that maintains tonal continuity while shifting the geometry in relief.

Powering the watch is the Cal. A&S8300, a manual winding movement measuring 2.97 mm in thickness. Despite its slim profile, it delivers a 100 hour power reserve and drives a one minute flying tourbillon at six o clock. The movement is visible through a sapphire caseback and finished with radiating Côtes de Genève, along with a hand engraved tourbillon bridge in yellow gold.

On the front, the tourbillon cage incorporates symbolic elements including a stylised sextant and an anchor shaped counterweight, referencing Arnold’s role in marine chronometry and longitude calculation.

The case measures 41.5 mm in diameter and 8.4 mm in thickness including the crystal. It is available in 18k 5N red gold or platinum, with each version limited to eight pieces.

Movement: Calibre A&S8300, manual winding, flying tourbillon, 21,600 vph, 100 hour power reserve
Functions: Hours, minutes, and flying tourbillon
Case: 41.5mm x 8. mm, 18k red gold or platinum
Dial: Polished onyx dial with concave onyx sub dial
Strap: Black alligator leather strap
Availability: Limited to 8 pieces in red gold and 8 pieces in platinum
Water resistance: 30m
Price: CHF 74,600 in red gold, CHF 85,400 in platinum