ARNOLD & SON - HM PIETERSITE - Pendulum
Arnold & Son | News
8 April 2026
ARNOLD & SON – HM PIETERSITE
ARNOLD & SON – HM PIETERSITE image of Pendulum
ARNOLD & SON – HM PIETERSITE image of Pendulum

A time for quiet storms

The most beautiful dials tell a story. Made from pietersite, the dial of the HM evokes an instant of a storm, like waves breaking on the coast of Cornwall, the birthplace of John Arnold. Available in red gold or steel, this design pays tribute to the ingenuity of the English watchmaker, while applauding the spirit of those who stay their true course in the face of the world. Arnold & Son presents its HM model in two new powerfully evocative versions.

The stone of storms

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.

The history

In 1714, the British Parliament responded to the challenges of the ocean by offering a £20,000 reward to anyone who could determine longitude at sea. While John Harrison (1693–1776) was the first to demonstrate that a timekeeper could solve this challenge, it was John Arnold and his precise, serially produced marine chronometers who enabled England, from the second half of the Age of Enlightenment, to embark on the exploration of new lands before any other nation.

The name

For this ultra-thin watch, Arnold & Son deliberately chose the designation HM to indicate that it displays only hours and minutes. It is inspired by the names of Royal Navy vessels where HM stands for His or Her Majesty’s (depending on the reigning monarch), reflecting the ships’ official status and royal authority. Appearing in the 17th century and formalised as HMS (His/Her Majesty’s Ship) at the end of the 18th century, here this historical reference is elegantly transposed to watchmaking – but that’s another story…

ARN_HM Pietersite_RG
ARN_HM Pietersite_RG

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.

Understated elegance

This timepiece, which is minimalist in appearance only, is worn on a matt blue alligator leather strap, perfectly matching the colour of the pietersite, and fastened with a traditional pin buckle, made from the same metal as the case.

ARN_HM Pietersite_ST_Back
ARN_HM Pietersite_ST_Back