ith its graceful curves and wide apertures, Ultrathin Tourbillon Skeleton also stands out for its slimness. Its new case, with a diameter of 41.5 mm and a thickness of 8.4 mm, presents the flying tourbillon calibre in its purest expression. The Ultrathin Tourbillon Skeleton collection, adorned in red gold or platinum, is issued in two limited series featuring 28 watches apiece.

Arnold & Son continues its tour of the Ultrathin Tourbillon collection. The A&S8320 calibre unveils its curves, apertures and details within a 41.5 mm case in either red gold (5N) or platinum (PT 950), each released in a run of 28 timepieces. Encased in this precious housing, Arnold & Son’s flying tourbillon stands out for its finesse and precision.

Finesse, because at just 3.3 mm thick, it is one of the slimmest skeleton tourbillon calibres in existence. Precision, because this one-minute flying tourbillon is assembled with a variable-inertia balance for enhanced calibration stability.

The purpose of a skeleton is to convey a message, be it geometric, generic or minimal. For Ultrathin Tourbillon Skeleton, the skeletonisation of the calibre reveals pronounced curves and numerous inflection points that are highlighted by an original finish. On both the Ultrathin Tourbillon Skeleton Red Gold and Platinum, the bridges are treated with rose-gold PVD (4N) after being decorated with radiating Côtes de Genève stripes.

The flange around the calibre adopts this same finish, clearly revealing the Arnold & Son signature at 6 o’clock and enabling the off-centred white opal dial to be displayed in its purest form.

At the heart of the Ultrathin Tourbillon Skeleton beats the A&S8320 calibre, whose architecture and slimness are its principal protagonists. Designed without an upper bridge to minimise its thickness, the calibre is classed as a flying tourbillon.

The variable-inertia balance with inertia blocks ensures more precise calibration over time. The slender triangular carriage is supported by a double arrow, which is actually a counterpoise. The arrowhead on the staff of the escape wheel serves as a seconds pointer, as the carriage completes one rotation per minute.

The changes to the tourbillon carriage and regulating organ give the A&S8320 calibre a power reserve of 100 hours. While this is a larger power reserve than for standard tourbillons, particularly slim ones, it is entirely in line with the performance regularly achieved by Arnold & Son calibres.

TECHNICAL SPECIFICATIONS

References
red gold: 1UTBR.Z01A.C246R
platinum: 1UTBX.Z01A.C245X

Movement

• Calibre A&S8320, 1-minute flying tourbillon, manual winding
• Jewels 29
• Diameter 32.00 mm
• Thickness 3.30 mm
• Power reserve 100 hours
• Frequency 3 Hz / 21,600 vph
• Finishes
  mainplate: skeletonised, rose-gold PVD treatment (4N), Côtes de Genève stripes radiating from the centre
  bridges: skeletonised, rose-gold PVD treatment (4N), polished and chamfered by hand, Côtes de Genève stripes radiating from the centre
  wheels: circular satin-finished
  screws: blued and chamfered, mirror-polished heads
  tourbillon carriage: ‘Arnold & Son’ signature, polished, satin-finished and chamfered by hand

Functions

• hours, minutes

Dial

• white opal

Case

• Material 18-carat (5N) red gold or platinum (PT 950)
• Diameter 41.50 mm
• Thickness 8.40 mm (with crystal)
• Crystal domed sapphire with an anti-reflective coating on both sides
• Case back sapphire crystal with an anti-reflective coating
• Water-resistance 3 bar (30 metres/100 feet)

Strap

• Material
  red gold: blue alligator leather, black alligator leather lining, hand-stitched
  platinum: brown alligator leather, black alligator leather lining, hand-stitched

Clasp

• folding clasp in titanium with cover in 18-carat (5N) red gold or platinum (PT 950)

Limited edition
red gold: 28 timepieces
platinum: 28 timepieces

Swiss retail prices
red gold: CHF 74,400 incl. tax (subject to change)
platinum: CHF 86,200 incl. tax (subject to change)