Constant Force Tourbillon 11 Platinum: Arnold & Son’s Final Opus

Arnold & Son closes the Constant Force 11 collection with an 11-piece platinum edition. Hand-guilloché dial, A&S5219 calibre, CHF 140,600.

Collector Notes

• Limited to 11 pieces in platinum (Pt 950), reference 1FCBX.Z01A.C0232X, with an 18-carat yellow gold hand-guilloché dial and a Swiss retail price of CHF 140,600 incl. VAT.
• Powered by the in-house A&S5219 manual-winding calibre with a patented constant force mechanism and one-minute tourbillon; 100-hour power reserve.
• The final opus of the Constant Force 11 collection, closing Arnold & Son’s 260th-anniversary series that opened with a gold edition.
• The tourbillon cage faithfully reproduces the design of the first tourbillon Abraham-Louis Breguet presented to John Roger Arnold in 1808, now conserved by the British Museum.

Design & Mechanics

Eleven pieces. That constraint alone defines the weight of this release before a single technical detail is considered.

The solid gold dial carries a “tremblé” guilloché surface engraved by hand with a burin. The tool traces irregular zigzags that read as the curling fronds of Cornish fern, referencing the moorland around Tintagel, birthplace of John Arnold. The pattern is pierced to accommodate a white opal concave subdial for hours and minutes, and to expose the constant force mechanism beneath its 18-carat gold bridge.

The platinum case measures 41.5mm in diameter and 13.7mm thick. Water-resistant to 3 bar, it is fitted with a domed sapphire crystal, anti-reflective on both sides, and worn on a hand-stitched midnight blue alligator strap secured by a platinum folding clasp.

Movement & Materials

The A&S5219 calibre positions its constant force mechanism between the main gear train and the tourbillon, eliminating torque variation across the full 100-hour power reserve.

Each second, the mechanism rearms a finely adjusted spiral and advances the hand-blued anchor one increment. That anchor doubles as a structural bridge, so the true-beat seconds display is an integral part of the architecture rather than an added complication. The tourbillon cage, with its mirror-polished and rounded bridge, reproduces the cage design Breguet used in the 1808 piece now held by the British Museum.

Market Position

At CHF 140,600, the Constant Force Tourbillon 11 Platinum sits at the upper tier of independent-spirit haute horlogerie. For Gulf collectors, that figure places it alongside comparable limited tourbillons from Geneva’s most historically grounded makers, with the added distinction of a verifiable museum-housed prototype as its direct ancestor.

Scarcity reinforces the position. Eleven pieces for a global collector base is not a commercial edition; it is a commemorative object. The Perpetual Moon Blue demonstrated Arnold & Son’s capacity to produce visually arresting, mechanically distinctive pieces at scale; this platinum edition operates in an entirely different register.

Heritage & Lineage

On the barrel bridge, Arnold & Son has hand-engraved the inscription: “To the revered memory of John Arnold and Abraham-Louis Breguet. Friends in their time, legendary watchmakers always.” This text, placed where a collector will see it every time the watch is opened for service, anchors the object within a specific historical relationship rather than a generalised claim to heritage.

The finishing of the main plate and tourbillon cock mirrors that of the original 1801-era tourbillon. That fidelity is the edition’s clearest argument for long-term relevance: ownership of piece eight of eleven is, at some level, ownership of a footnote to British Museum catalogue.

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