Arnold & Son HM Pietersite
Apr 17, 2026
HM Pietersite
A time for quiet storms
The most beautiful dials tell a story. Crafted from pietersite, the HM dial instantly evokes the crashing waves of Cornwall’s coast, John Arnold’s birthplace. Available in red gold or steel, this design pays tribute to the ingenuity of English watchmaking and celebrates those who remain true to their path despite the world’s challenges. Arnold & Son presents its HM model in two powerfully evocative new versions.
What is Pietersite?
This decorative mineral, sometimes called the ‘stone of storms’, is a variety of chalcedony. It was discovered by Sid Pieters in Namibia at the beginning of the 1960s. It was selected by Arnold & Son for its delicate, swirling, random patterns that recall the skies of Cornwall during rough weather and the foaming waves that lash the rugged coasts of the county.
An extremely fine watch
With a diameter of 39.5 mm, the watch’s dreamlike dial enchants with its unique diaphanous patterns, inviting us to follow the movement of their curls. Presented in 18-carat red gold (5N) or steel, it is remarkable for its elegance and finesse. The case is only 7.82 mm thick. Delicate and expressive, the HM displays hours and minutes with restraint. Produced in a limited edition of just 8 pieces in gold and 18 in steel, the model is water-resistant up to 30 metres, perfect for daily use in all levels of humidity.
An ultra-thin calibre
Part of the family of dress watches, the Arnold & Son HM is driven by an in-house manual winding calibre bearing the reference A&S1001. Visible through the transparent case back, this ultra-thin movement, carefully finished according to the most exacting standards of luxury watchmaking, measures 30 mm in diameter and is only 2.70 mm thick. Its rhodium-plated main plate features a circular-grained finish. The bridges are chamfered with a radiating Côtes de Genève decoration. The wheels are snail-finished and the screws, chamfered with polished heads, are blued.
Exceptional performance
This prestigious movement, equipped with a regulating organ oscillating at 21,600 vibrations per hour (3 Hz), offers a generous 90-hour power reserve once the barrel has been fully wound via the winding crown.
