Just days away, Only Watch 2015 will see 43 unique timepieces go under the hammer, with all proceeds going to a Monaco charity that funds research into Duchenne muscular dystrophy.

The brands that have contributed timepieces to the auction comprise watchmaking’s finest, encompassing establishment names like Patek Philippe and Vacheron Constantin, to independent watchmakers like F.P. Journe and Voutilainen. Even Tudor is taking part, marking the first time ever it has made a one-off timepiece. Here’s a look at our top ten picks from the sale.

Lot 4: Jaquet Droz Petite Heure Minute Paillonnée Only Watch

The paillonnée dials are amongst the most beautiful enamel dials done by Jaquet Droz, a brand that is known for its lavish dial. Paillons refer to the tiny spangles used to create decorative patterns in the enamel. In this case the paillons are tiny bits of gold formed into a baroque leaf motif interspersed with flowers.

Usually produced in blue enamel, this one of a kind Paillonnée dial is in rich red enamel, paired with a rose gold case. This is estimated at SFr37,000 to SFr47,000.

Lot 6: Laurent Ferrier Galet Square in stainless steel

A subtle tweak to the case shape of the Galet Square makes this a unique piece with a decidedly vintage look reminiscent of 1920s wristwatches. Instead of the tapered lugs on the ordinary model, Laurent Ferrier has given this straight lugs topped with screws on each end, while the dial is a “sector” style dial. Simple as it is on the front, the movement is elaborately constructed and decorative, and still one of the most refined self-winding movements in production. This is SFr30,000 to SFr40,000.

Lot 8: Leroy Chronometre Observatoire

The unique Chronometre Observatoire just got even more unique as Leroy‘s chief executive recently revealed the L200 movement inside will not make it to commercial production, being too complex and expensive. So the piece for sale – featuring a case, dial, movement bridges and base plate in aluminium – is essentially a one of a kind prototype. (We recently explained why this movement is so challenging.) The estimate is SFr30,000 to SFr40,000.

Lot 10: Louis Vuitton Escale Worldtime “The World is a Dancefloor”

This is a variation on Louis Vuitton‘s instantly recognisable world time wristwatch developed by the team at movement specialist La Fabrique du Temps. The hand-painted, technicolour dial is executed in a different palette, and the arrow for the minute pointed is rendered to resemble a dance floor. The estimate is SFr60,000 to SFr70,000.

Lot 13: F.P. Journe Tourbillon Souverain Bleu

What will probably be the most expensive wristwatch by an independent watchmaker at Only Watch 2015, the Tourbillon Souverain Blue combines F.P. Journe‘s trademark tourbillon movement with the style and material of his entry-level Chronometre Bleu wristwatch. This is estimated at SFr250,000 to SFr400,000 and you can find out more about it in our story published earlier.

Lot 16: Patek Philippe reference 5016A

With a stainless steel case and blue enamel dial, this is a unique version of a discontinued Patek Philippe grand complication wristwatch featuring a perpetual calendar, tourbillon and minute repeater. Estimated at SFr700,000 to SFr900,000, this will surely be the most expensive watch in the Only Watch sale. It will surely blow past the estimate and might just become the most expensive modern Patek Philippe wristwatch ever sold. See it in greater detail here.

Lot 21: De Bethune DBS Piece Unique

This one of a kind DBS harks back to the first Only Watch event in 2005, when De Bethune created another unique variant of the DBS for the augural auction. The form of this year’s DBS is typical of the model, with the crown at 12 o’clock and bullet-shaped lugs. Each of the hour markers is spheres of blue titanium – a metal synonymous with De Bethune – while the hands are blued steel. An exceptionally large “Piece Unique” label across the dial serves as a reminder to the owner of he good he did by buying this watch. The estimate is SFr65,000 to SFr75,000.

Lot 34: Vacheron Constantin Métiers d’Art Mécaniques Ajourées Skeleton

Based on Vacheron Constantin‘s recently introduced skeleton wristwatch, the Only Watch edition is distinguished by its red enamel chapter ring and discreet “Only Watch” logo at three o’clock. Practically every surface of the movement is hand-engraved, both front and back. This is estimated at SFr70,000 to SFr80,000.

Lot 38: Voutilainen GMT-6 Only Watch

One of the rare Voutilainen wristwatches to feature an enamel dial, the GMT-6 for Only Watch is dual time with a sub-dial at six o’clock serving as the second time zone display as well as a day and night indicator. It’s different from the regular production model due to the dial: the central portion is a rich blue enamel, while the sub-dial is in blue and gold enamel. Both are executed with a champleve technique that applies translucent enamel into a guilloche disc of gold. The estimate is SFr90,000 to SFr100,000.

Lot 41: Bell & Ross BR 01 Skull Bronze Tourbillon

With a case made of heavily aged bronze, the Bell & Ross BR 01 Skull Bronze Tourbillon is one of the most striking timepieces of the Only Watch line-up. It’s meant to look like a long lost, pirates’ treasure, hence the skull on the dial (made of solid gold and hand- engraved) and cutlass-shaped hands. This is lot and it’s estimated at SFr100,000 to SFr120,000.

Auction details

Only Watch 2015 takes place at 3:00pm on November 7, 2015 at Hotel La Réserve in Geneva. There will be no buyer’s premium levied on winning bids at Only Watch, and the entirety of the sale price will go fund research into Duchenne muscular dystrophy. The full catalogue is available here, while the absentee bid form can be downloaded in PDF format.

Simplifying its trademark perpetual calendar to the minimal, H. Moser & Cie. introduces the Venturer Big Date featuring an extra-large date display.

H. Moser & Cie. began with only one watch, the cleverly constructed and concise Endeavour Perpetual Calendar featuring an instantaneous calendar display. Now that flagship complication has been stripped of its fancier functions, leaving just the date display, creating the Venturer Big Date, offering the essence of the firm’s ingenious calendar movement at a more accessible price. Because the HMC 100 movement inside the Big Date is essentially a heavily simplified version of the movement in the perpetual calendar, the Big Date includes several of its bigger brother’s innovations. That includes the oversized date display on a single plane, meaning the date is not shown using two discs on separate levels as on Lange watches for instance. But because the movement is not large enough to accommodate all the oversized digits on one disc, it’s actually comprised of two superimposed discs, with a window on the upper disc to show the dates from 16 to 31.

The date changes in a blink of an eye at midnight, instead of crawling over several hours as is typical of most movements. And it is also a robust mechanism that can be set both forwards and backwards, at any time, even when the date is in the midst of changing.  Even the setting mechanism is unique to Moser – the crown requires an initial pull and release, and then a second pull outwards to set the time. This means the date will not be inadvertently adjusted instead of the time. Put simply, it is idiot proof and almost impossible to damage, but the mechanics behind this convenience are complex.

Like other Moser watches equipped with its top of the line movements, the HMC 100 inside the Big Date has an interchangeable escapement which can be swapped during servicing for faster turnarounds. And the escape wheel and pallet fork are made of hardened, 18k gold.

Being the second model in the Venturer line after the Small Seconds, the Big Date retains the characteristic look with a domed dial and narrow bezel. The case is 41.5mm in diameter and available only in red gold for now. Dial options are either silver or graduated, red gold fumé. The Venturer Big Date is SFr29,000 or US$29,000. That’s just under half the retail of the Endeavour Perpetual Calendar. 

More than just a one-off dial and case, the L. Leroy Chronomètre Observatoire will be the only one ever made as the L200 movement inside will not make it into series production, being too complex and expensive.

The flagship wristwatch of Leroy was to have been the Chronomètre Observatoire powered by the calibre L200, which is why a one-off variant entirely in aluminium was created for high profile charity auction Only Watch. But it recently became even more unique, as revealed to exclusively to us by the chief executive of L. Leroy: because the ambitions of L200 movement exceeded commercial reality, the L200 will never make it into series production, meaning the Only Watch edition will be truly singular.

A storied name in French timekeeping shared by several watchmakers, including Pierre Le Roy, a contemporary of Ferdinand Berthoud, the resurrected Leroy name is a maker of chronometer wristwatches part of the group that owns movement maker Soprod, giving it the engineering and manufacturing expertise needed to produce reliable movements.

Most recently Leroy debuted a pair of impressively complex movements (including the L200 seen here) heavily inspired by classical watchmaking, both the work of Karsten Frasdorf, a talented movement constructor whose past movements, most notable at Fabrication De Montres Normandes (FDMN) and Heritage Watch Manufactory, have always been too sophisticated for commercially viable production.

The lozenge-shaped power reserve window at nine o’clock

Mechanical ambitions inspired by history

And so it is with the L200 inside the Chronometre Observatoire. The aluminium base plate of the L200 movement in the Only Watch timepiece is marked “P01”, indicating this was the first prototype made. But as it turns out it will be the only one ever made. The L200 is a hand-wound movement with an four day power reserve, powered by twin barrels wound with a grand sonnerie-style winding click. But what makes the calibre special, and too elaborate for series production is the regulator. It has a Robin escapement, or natural escapement, a type of direct impulse escapement, a precision escapement found in some marine chronometers. Because of the nature of the escapement, the seconds hand moves in two-step jumps, a small tick followed by a longer one.

Like the detent escapement, the duplex works with little fiction, but requires a little shake to start up. And more importantly, sudden shocks can stop it completely, which is why it’s never been implemented in wristwatch movements. Similarly, the hairspring is no ordinary hairspring, being formed with double terminal curves, inwards and outwards, to improve the concentricity of the balance spring. Just as interesting is the large balance wheel, which has a diameter almost half that of the movement, an abiding principle in classical watchmaking. As is traditional for a high-end chronometer movement, it is free-sprung, with adjustable weights on its rim for poising.

What makes it special is the fact that it is contained inside a Brun cage. A regulator invented by M.J. Brun in the early 20th century (examples of his work reside at the International Museum of Horology in La Chaux-de-Fonds), the Brun cage contains the balance wheel and can be rotated for regulating. Turning the Brun cage moves the position of the balance spring stud, changing the starting point of the hairspring, allowing it to be positioned optimally.

The balance inside the Brun cage

The once (and future?) precious metal

Beyond the movement construction, the Only Watch edition is also unusual for its material: the case, dial, movement bridges and base plate are made entirely of aluminium. This was inspired by a grand sonnerie carriage clock made by Le Roy in 1894 that was housed in an aluminium case (below).

The reason an expensive clock was made of what is today an inexpensive metal is the fact that aluminium was once a precious metal comparable to gold. Before the Hall-Heroult process to smelt aluminium cheaply was invented in 1886, aluminium was exceptionally expensive to refine.

Lot 8 in the Only Watch auction, the Chronometre Observatoire Only Watch carries an estimate of SFr30,000 to SFr40,000. Only Watch takes place in Geneva on Saturday, November 7, 2015; there is no buyer’s premium for the auction and all proceeds from the event going to support research into Duchenne muscular dystrophy. Bidding can be done via telephone, online or in-house. Registration to bid can be done here.

Correction November 16, 2015: Edited to reflect the fact that the power reserve is four days, not eight as previously stated, and also that Pierre Le Roy was a contemporary of Berthoud, and not Breguet. Also to reflect that the L200 movement features a Robin or natural escapement.