Perpetual Moon 38 White Gold Aventurine

Perpetual Moon 38 White Gold, Aventurine Edition

A beacon in the night
Arnold & Son’s vision of feminine watchmaking shines in all its splendour, dazzling in daylight and bewitching come nightfall. For a new edition of the Perpetual Moon 38 is joining the astronomical constellation of Switzerland’s most British watchmaking house. Its blue aventurine glass dial, peppered with gleaming fragments, evokes a starry sky. The 38 mm polished white gold case reflects a cool light, while the bezel and lugs are set with glittering white diamonds. Taking centre stage is the astronomical moon: a luminescent disc of mother-of-pearl that travels along its trajectory amid the hand-painted constellations of Ursa Major and Cassiopeia. Presented as a limited edition of 18 timepieces, the Perpetual Moon 38 White Gold, Aventurine Edition gracefully blends the poetry of light with watchmaking excellence.                                                                            

Dazzling brilliance
This version dresses the Perpetual Moon 38 in a precious white gold case, embellished with exquisite gem setting. Brilliant-cut diamonds adorn the bezel, lugs and buckle, while marquise-cut diamonds highlight the appliqué hour-markers, totalling approximately 2.66 carats and bestowing remarkable radiance on the Perpetual Moon 38 White Gold, Aventurine Edition.

With its astronomical concept, this jewellery creation remains anchored in the watchmaking know-how of the La Chaux-de-Fonds Manufacture. It is powered by an extremely precise manually wound movement that perpetuates the excellence of John Arnold, the English master watchmaker whose relentless pursuit of precision defined his era. 

A succession of stars
Every detail on the Perpetual Moon 38 White Gold, Aventurine Edition honours the spirit of its lunar complication. The aventurine dial, peppered with metallic fragments, evokes distant stars twinkling in the night sky. A generously sized aperture displays a broad disc, also in aventurine, that features the mother-of-pearl moon adorned with meticulously hand-painted shadows.

In keeping with the tradition of the collection, the moon is framed by the constellations of Ursa Major and Cassiopeia, which are also hand-painted and enhanced with luminescent material. This choice is a nod to the history of John Arnold, who pioneered marine timekeeping. These two constellations have guided sailors since time immemorial. Halfway between them is Polaris, the Pole Star. Its fixed position invariably points north and its altitude can be used to calculate latitude. Prior to the invention of instruments that measure longitude, it was the only reliable landmark at sea. 

The Perpetual Moon 38 White Gold, Aventurine Edition thus reveals two faces: by day it displays a polished white gold case paired with a shimmering, deep blue dial; and by night, its more mysterious side emerges as its components, coated in Super-LumiNova, light up in a shade of icy blue. It is then that the moonlight eclipses the sparkle of the diamonds and fully asserts its poetic power.

A feminine mechanism
This timepiece takes the exacting watchmaking standards that have always driven Arnold & Son and transposes them to the world of women’s watches. To achieve this, the Swiss Manufacture developed a bespoke movement – the smallest in its collection. Measuring 30 mm in diameter, the A&S1612 calibre was specifically designed to fit perfectly inside the 38 mm case, which is only 10.44 mm thick. This movement with manual winding continues the house’s tradition of calibres with long power reserves by offering a remarkable 90 hours of autonomy. 

Astronomical poetry
The moon phase is the star complication of the A&S1612 calibre. It is indicated by a large moon disc, in keeping with the identity of the Perpetual Moon collection. Between 10 and 2 o’clock, the different crescents exactly reproduce the visible phases of the lunar cycle.

To uphold its watchmaking tradition, Arnold & Son has endowed this complication with incredible precision: after 122 years of uninterrupted operation, its mechanism will only lag behind by one day. This feat demonstrates the Manufacture’s commitment to achieving astronomical accuracy.

Technical specifications

Functions                     

• hours, minutes, astronomical moon phases

Movement

• Calibre: A&S1612, hand-wound mechanical
  
• Jewels: 24
  
• Diameter: 29.4 mm
  
• Thickness: 4.95 mm
  
• Power reserve: 90 hours
  
• Frequency: 3 Hz / 21,600 vph
  
• Finishes               
  mainplate: rhodium-plated, circular-grained 
  bridges: chamfered, radiating Côtes de Genève stripes
  wheels: golden finish, circular-grained
  screws: blued and chamfered, polished heads                                    

Dial                               

• blue aventurine glass
• hour-markers set with 12 marquise-cut diamonds

Moon phases                

• sky: blue aventurine glass
• moons: mother-of-pearl with added Super-LumiNova
  
• Cassiopeia and Ursa Major constellations: hand-painted, with added Super-LumiNova

Case

• Material: 18-carat white gold

  bezel, lugs and crown set with 80 brilliant-cut diamonds

• Diameter: 38 mm
  
• Thickness: 10.44 mm
  
• Crystal: domed sapphire, with an anti-reflective coating on both sides 
  
• Case back: sapphire crystal, with an anti-reflecting coating
  
• Water-resistance: 30 m / 3 ATM 

Strap

• Material: Midnight-blue satin alligator leather
• Pin buckle: 18-carat white gold, set with 22 brilliant-cut diamonds

Diamonds                

• total weight: ~2.66 carats
• colour: D-E-F
• clarity: IF-VVS

References 

• aventurine: 1GLMW.A01A.C0226W                               

Edition 

• aventurine: 18 timepieces

Astronomy, Chronometry and World Time

Arnold & Son's three founding principles

Throughout human history, measuring time has always referred to the stars. It was by observing certain stars and understanding their cycle that the first calendars were established with impressive accuracy. It took several millennia before this precision was enclosed in a timepiece like the ones designed by John Arnold. 

The golden age of maritime explorations and discoveries ushered this precision into a new technical ideal – determining longitude at sea. Its immediate corollary was the identification of local time, which changed constantly as the observer moved along an east-west axis. Astronomy, chronometry and what we now call world time are thus inextricably linked within one and the same question, to which John Arnold and his son devoted their lives, their art and their genius. 

This is how these three dimensions – astronomy, chronometry and world time – have come to be embodied in the House's contemporary timepieces.  Echoes of John Arnold's inventions and preoccupations, these pillars represent the foundations on which the Arnold & Son collections are based.

Chronometry: Be accurate

Rate accuracy, which is known as chronometry, is the key requirement of Arnold & Son's contemporary watchmaking. It is the standard of excellence for its collections, the first condition to be met and constantly checked, whether it is at the forefront or in the background of a watch designed by Arnold & Son. It is the most discreet of a movement's characteristics. 

When building an Arnold & Son collection, all the thinking is focused on this chronometry. The manufacture calibres are based on advanced technical fundamentals that are not necessarily the best known. One of them is the choice of small, lightweight balances capable of rapidly returning to their isochronous rate after the latter has been disturbed by inevitable everyday shocks. Another is the routine use of large barrels or even two series-coupled barrels to store the energy required for the movement to function.  They consequently provide Arnold & Son's manual winding calibres with above-average power reserves of 90 hours and more. A third is the particular attention paid to manufacturing the gear trains, roller-burnishing the pinions and polishing the gear teeth, as well as the precision of the machining and therefore the relative positions of the moving parts, a key concept in rate accuracy.

The tourbillon (or the fact of putting the regulating organ in rotation on its axis to best adjust the effects of gravity on the balance and its hairspring) was patented after John Arnold's death, but it was undoubtedly at the heart of his chronometric research and discussions with his friend Abraham-Louis Breguet, who incidentally assembled his first tourbillon on a John Arnold pocket watch in homage to this great watchmaker. Nowadays, the tourbillon has become a must in Arnold & Son collections.

While the tourbillon was not a complication in John Arnold's time, constant force underpinned the design of his marine chronometers. The regularity of the rate of the sprung balance relies on the consistency of the energy that it receives. However, this naturally fluctuates due to the circular and spiral nature of the mainspring contained in the barrel. To achieve a perfectly smooth torque, in other words a constant force, Arnold & Son uses a one-second constant-force mechanism. Housed just before the escapement, it stores up a small but always equal amount of energy in a secondary spring, the remontoire. Thus, every second, the sprung balance receives very precisely the same force to power its oscillations. These become more even, thereby creating the conditions for a high-precision rate.

Arnold & Son also works with another of John Arnold's historical chronometry indicators: deadbeat seconds, a mechanism that was indispensable to navigators at the time for calculating longitude. This mechanism advances one step each second, rather than six or eight smaller jumps in sync with the frequency of the balance. Instead of the term deadbeat seconds, Arnold & Son prefers a name whose very sound means accuracy: “true beat second”. Its jump is a signature of John Arnold's marine chronometers and a complication that is still alive and well in the House's collections.

Astronomy: Under the sky

The Pole Star, Southern Cross, astrolabes and sextant: measuring time has relied on the recurrence of astronomical phenomena in order to find long, reliable points of reference there that can be used under any conditions. The fruit of the human ingenuity, patience and dedication of countless observers and astronomers from every culture, these markers of cyclical time are foundational for Arnold & Son watchmaking.

Astronomical complications are a signature of Arnold & Son collections, with the moon as the heavenly body of choice, main subject and major inspiration. The distinctive feature of the Brand's moon phase timepieces is that they feature “astronomical” display precision as a matter of course. This term corresponds to an accumulated one-day deviation in the moon phase display every 122 years. Since setting this complication requires great finesse, the Arnold & Son moons generally have a double display with a secondary indicator on the case back next to the movement. This extremely rare display bears witness to Arnold & Son's involvement in all types of development and reflects its favoured themes, which are as much chronometric as astronomical.

Over and above their precision, Arnold & Son's moon phases attract all the light, either with a large moon opening up over half the dial, or with a 12-mm three-dimensional rotating moon, making it the largest of all moons. Whether in two or three dimensions, the moon is always treated as a small work of artistic craftsmanship, composed of materials that are rare in watchmaking such as marble or Paraíba tourmaline, or delicate such as mother-of-pearl, meteorite or aventurine glass. The Arnold & Son moon also shines at night, often with a subtle addition of luminescent material. 

World Time: Here, elsewhere, everywhere

With ocean navigation, humankind divided up the world and invented longitudes, which were calculated by comparing the local time, observed using the sun, and the time at a starting point, kept by an extremely reliable timepiece. John Arnold was one of the leading suppliers of chronometers to the British Navy. He was the one who successfully improved the reliability and simplified the production of these indispensable marine chronometers, so much so that he became a benchmark among great explorers such as James Cook and later Dr David Livingstone. The indication of several time zones is therefore integral to Arnold & Son's watchmaking identity.

As this navigation was itself inseparable from cartography, for this world time complication Arnold & Son has chosen to depict a three-dimensional terrestrial hemisphere, making it possible to tell what time it is at any point.

In parallel to this graphic vision, Arnold & Son has developed a second approach to the time elsewhere in the world: with a double tourbillon featuring two distinct rotating regulating organs, making it possible to follow time zones offset by 15, 30 or 45 minutes compared to a full hour – a freedom in terms of setting that remains extremely rare. 

Once again, and because this double display is based on a profoundly chronometric complication, Arnold & Son’s fundamental principles are interwoven. One never advances alone; there are always two – if not three – together. This is how a pillar's strength is measured: it relies on the next one, creating the conditions for a solidity that stands the test of time.