legant in its symmetry. Refined in its detail. Relevant in its strong horological focus. Nebula 40 Steel is a one-of-a-kind skeleton timepiece in which Arnold & Son combines style and substance, movement and design. The star-shaped arrangement of its seven bridges and even its name, Nebula, create a coherent system: the radiating concept that governs the form of Nebula 40 Steel and determines its structure, topography and depth.

Following the launch of Nebula 40 Steel in black and a gold edition celebrating John Arnold’s 260-year legacy, variations on this skeletonised piece are enriched with blue tones.

Radiating towards the centre, the bridges are arranged around the edge of the main plate, itself formed of intersecting curves. These bridges meet in the middle to give Nebula 40 Steel its structural integrity and provide additional anchor points for the movement’s components.

Just as each bridge follows the last in quick succession, the organs inside the A&S5201 calibre are arranged in a peripheral kinematic chain. The two large barrels that provide Nebula 40 Steel with a 90-hour power reserve, as well as the balance and small seconds, are positioned along four lines of symmetry. This equilibrium is one of the signatures of the collection.

Nebula 40 Steel also comes to life thanks to a host of details stemming from Arnold & Son’s technical requirements, which produce an understated aesthetic effect. These include the openworked bridges with chamfered edges, and the crown mechanism, which has been inverted and transposed to the case-back side to create symmetry with the first wheel at 9 o’clock. The same is true of the wide click spring, which controls the unwinding of the first barrel; the appliqué hour-markers, which have the same faceted design as the hands; and the proportions of the 40 mm-diameter case, which is balanced by a thickness of 9.10 mm to ensure complete elegance on the wrist.

Last but not least, Nebula 40 Steel, Blue Edition is a confluence of colours. As its name suggests, the dominant shade is the blue of the movement. All the lower levels of the calibre feature a blue PVD treatment, and this hue influences the finishes: horizontal satin on the dial side of the main plate, and Arnold & Son’s signature ‘Rayons de la Gloire’ motif on the reverse.

In contrast, the bridges, ratchets, cogs and even the balance have a palladium finish to echo the colour of the steel case. A blue strap in alligator leather or rubber completes the timepiece. Arnold & Son is also presenting a version with a three-link steel bracelet, whose understated design allows the balanced arrangement of the case and movement to truly shine.

TECHNICAL SPECIFICATIONS

Functions: hours, minutes, small seconds

Movement

• Calibre A&S5201, mechanical with manual winding
• Jewels 24
• Diameter 31.10 mm
• Thickness 4.18 mm
• Power reserve 90 hours
• Frequency 3 Hz / 21,600 vph
• Decoration
  main plate: blue PVD treatment, ‘Rayons de la Gloire’
  barrel covers: blue PVD treatment
  bridges: palladium-treated, polished and chamfered, satin-finished surfaces
  balance: rhodium-plated
  wheels: circular-grained and chamfered
  chatons: 18-carat gold
  screws: chamfered, with mirror-polished heads

Dial: flange with blue PVD treatment, rhodium-plated appliqués

Case

• Material: stainless steel
• Diameter 40 mm
• Thickness 9.10 mm
• Crystal: domed sapphire, double-sided anti-reflective coating
• Case back: sapphire crystal, anti-reflective coating
• Water-resistance 3 bar (30 metres/100 feet)

Strap

• Material: stainless steel, blue alligator leather or blue rubber
• Clasp: stainless steel, folding clasp on steel bracelet, pin buckle on alligator or rubber straps

References

• steel bracelet: 1NEGS.U01A.S135D
• alligator strap: 1NEGS.U01A.C1235S
• rubber strap: 1NEGS.U01A.K0243S

Swiss retail price

• steel bracelet: CHF 17,600 incl. VAT (subject to change)
• alligator strap: CHF 16,900 incl. VAT (subject to change)
• rubber strap: CHF 16,700 incl. VAT (subject to change)