This year at Baselworld I had the great pleasure to visit Ferdinand Berthoud booth and see the exceptional Chronomètre FB 1L. This is a new experimental collection, combining the in-house tourbillon movement with a new display of the age and phases of the moon.

Ferdinand Berthoud Chronomètre FB 1L Review
Ferdinand Berthoud Chronomètre FB 1L.1

Available in two ten-piece limited editions – with a case in 18-carat white gold and black ceramic lugs, or in anthracite ceramised titanium & sandblasted 18-carat white gold, this new collection displays the hours and minutes on a dedicated subdial at 12 o’clock, seconds in the centre and the 53-hour power reserve on the back of the movement. A large hand at 6 o’clock indicates the age and phases of the moon in a continuous back and forth movement. This patent-pending complication, combined with the constant force of the FB-T.FC.L calibre, ensures astronomical precision corresponding to a one-day difference in 577 years of operation.

Ferdinand Berthoud Chronomètre FB 1L
Ferdinand Berthoud Chronomètre FB 1L.4

Truly at the crossroads between astronomy and chronometry, the Chronomètre FB 1L pays tribute to Ferdinand Berthoud's work on chronometric precision and the calculation of longitude. It was to this end that the master watchmaker designed his famous Marine Chronometers, which inspired the creation of the FB 1L collection.

The New Ferdinand Berthoud Chronomètre FB 1L
Ferdinand Berthoud Chronomètre FB 1L

A New Display

The FB 1L Chronometer is a model displaying the age and phases of the moon. Combining chronometric precision and astronomical measurement, it associates these two previously dissociated values which jointly made it possible – almost three centuries ago – to achieve more accurate longitude calculations, a quest at the heart of a large number of Ferdinand Berthoud's works.

The age and phases of the moon are two separate measurements.

The moon phase is the most common in watchmaking. This is the complication that visually indicates the different lunar cycles. The moon phase is divided into four phases: new moon, first quarter, full moon and last quarter. A lunation or lunar cycle is the time interval between two new moons. A symbolic and aesthetic complication, the moon phase does not, however, offer the accuracy necessary for astronomical use.

Ferdinand Berthoud Men Watches
Ferdinand Berthoud Chronomètre FB 1L

The age of the moon is a more accurate indicator which counts the number of days since the last new moon. This veritable scientific measuring instrument, coupled with the chronometric measurement of time, made it possible to determine longitude at sea with unparalleled accuracy nearly 270 years ago.

For the first time, the FB 1L collection combines these two instruments: a chronometer and an indicator of the age and phases of the moon within the same model.

Ferdinand Berthoud Chronomètre FB 1L Movement
Ferdinand Berthoud Chronomètre FB 1L

Constant Force

The 100% in-house calibre of the Chronomètre FB 1L features an original suspended fusee-and-chain construction. It delivers a constant force to the escapement throughout the operation of movement, from its first turn of the crown to complete winding, thus achieving a 53-hour power reserve.

Ferdinand Berthoud Chronomètre FB 1L Tourbillon Movement
Ferdinand Berthoud Chronomètre FB 1L

Tourbillon With Direct-Drive Seconds

The movement also features a tourbillon with direct-drive seconds, compensating for the variations in rate induced by the different positions the watch adopts throughout the day. Direct-drive seconds are made possible by the correlation between the seconds wheel and the wheel driving the tourbillon carriage.

Calibre FB-T.FC.L Movement
Calibre FB-T.FC.L

Age Of The Moon And Progression Of The Lunar Cycle

Finally, for the first time, Calibre FB-T.FC.L is complemented by a patented complication: the age of the moon. This consists of two indications. The first is the display of the moon's age in days, marked from 1 to 14 on a sector swept over by a hand moving back and forth.  Day "1" is the first day since the new moon. Facing this "1" is a circle symbolising the latter. The next three quarters are spread over the same sector as the days go by. Facing the 14th day is a solid disc, symbolising the full moon. At this point, the hand performs a gradual backward move passing through the same quarters in the opposite direction: three quarters, two quarters, one quarter, until the return to the new moon.

Ferdinand Berthoud Chronomètre FB 1L Dial
Ferdinand Berthoud Chronomètre FB 1L - Moon Display

This display of the age of the moon is complemented by another function revealed through a dial opening between 4 and 5 o’clock, showing the current moon phase, waxing or waning, thereby indicating whether the moon-age indicator hand is rising (up to day 14) or returning (to the new moon). Since this hand progresses at a rate imperceptible to the naked eye, this precious moon-phase indication makes it possible at a single glance to see whether one is heading towards a full moon or a new moon.

This age-of-the-moon display is provided by an arrow surrounding a half-sphere accurately depicting the two large faces of the Moon – visible and hidden – on both versions of the FB 1L collection.

Moon Phases Mecanism

This original mechanism is inspired by a system for displaying the equation of time developed by Ferdinand Berthoud in 1752. It was based on the use of a feeler-spindle arm that followed an equation of time cam. In this instance, however, it is an age-of-the-moon cam.

Ferdinand Berthoud FB-1L.4 moon details
Ferdinand Berthoud FB-1L.4 moon details

This invention earned him the title of master watchmaker a year later, by decree of the King's Council. This contemporary interpretation serves to provide a disc-free display of the age of the moon by means of a hand moving back and forth with an accuracy of 29 days, 12 hours, 44 minutes and 15 seconds – corresponding to a mere one-day difference in 577 years of continuous operation. This exceptional result is made possible thanks to the large number of teeth on the moving disc revealed between 4 and 5 o’clock. The Chronomètre FB 1L thus achieves a degree of accuracy in displaying the age of the moon that exceeds conventional moon phase displays, most of which remain accurate over a period of “only” 122 years.

The accuracy of each movement in this collection is attested by a chronometry certificate issued by the Official Swiss Chronometer Testing Institute (COSC).

The unique features of the Ferdinand Berthoud movement are the subject of four patents, now supplemented by two other patent applications for the age-of-the-moon mechanism specific to the FB 1L models.

Expensive Watches Ferdinand Berthoud Chronomètre FB 1L
Ferdinand Berthoud Chronomètre FB 1L


The distinctively shaped case is based on the architecture of the marine chronometers designed by Ferdinand Berthoud from 1760 onwards, inspired by his Marine Clocks, and their gimbal suspension in particular, which allowed the on-board chronometers to remain permanently in a horizontal position.

For the FB 1L collection, the case was completed for the first time with a selector switch placed between 4 and 5 o’clock which enables the wearer to choose between two positions, L and H, to set the age of the moon or the time.

Ferdinand Berthoud Chronomètre FB 1L
Ferdinand Berthoud Chronomètre FB 1L


Two versions of the Chronomètre FB 1L are available.

The FB 1L.1 "Near Side of the Moon" model favours a warm and luminous approach reminiscent of the visible face of the Moon and the intensity of the full moon. The piece has a case middle, side elements and crown in 18-carat polished white gold. Its lugs are made of black ceramic.

Top Expensive Watches
Ferdinand Berthoud Chronomètre FB 1L

The FB 1L.4 "Far Side of the Moon" version evokes the dark and mysterious tones of the Moon's hidden face. This time, its white gold case middle is sandblasted and, in place of ceramic, the lugs and side elements are made of dark grey ceramised titanium. On average four times harder than standard titanium, ceramised titanium is part of the sustainability approach adopted in the making of Ferdinand Berthoud creations, which has already led the Manufacture to develop a carburised steel with similar properties.

Each piece will be issued as a numbered ten-piece limited edition.

Ferdinand Berthoud Chronomètre FB 1L Watch Review
Ferdinand Berthoud Chronomètre FB 1L

Ferdinand Berthoud Chronomètre FB 1L

Technical specifications:


·       FB 1L.1 - 10-Piece White Gold Numbered And Limited Edition

·       FB 1L.4 - 10-Piece Anthracite Ceramised Titanium Numbered And Limited Edition


• Octagonal 18-carat white gold case with two transparent sapphire portholes and black ceramic lug elements or Octagonal case in anthracite ceramised titanium & 18-carat sandblasted white gold featuring two transparent sapphire portholes

Total diameter: 44 mm

Thickness: 13.95 mm

Water resistance: 30 metres

Crown diameter: 9 mm

Numbered edition: 01/10 to 10/10 for each version

• Dynamometric crown (uncoupling system) in 18-carat white gold with black ceramic medallion

• Knurled 18-carat white gold L/H (Moon/Time) selector, titanium mechanism, on the side of the case middle between 4 and 5 o’clock

• Screw-down case-back in 18-carat white gold fitted with a glare-proofed sapphire crystal

• Domed and arched sapphire crystal with anti-reflective treatment on both sides


• Moon plate (dial) in rhodium-plated or black PVD-coated sandblasted brass

• Hours and minutes on a rhodium-plated or black PVD-coated brass counter at 12 o’clock, circular satin-brushed finish and matt in the centre

• Toothed feeler-spindle with steel spring at 9 o’clock

• Lunar cycles and age of the moon cartouche in satin-brushed rhodium-plated or black PVD-treated brass with black-varnished engraved scale

• “Near side of the Moon” or “Far side of the Moon” half-globe in engraved, rhodium-plated brass between 4 and 5 o’clock

• Flat inner bezel ring with seconds around the dial rim in rhodium-plated or black PVD-treated brass with black or grey-varnished engraved scale



• 18-carat blued or white gold dagger-shaped facetted cut-out hours and minutes hands

• 18-carat blued gold or Rhodium plated carat gold arrow-shaped power-reserve hand (on the back of the movement)

• Blued bronze or Rhodium plated bronze central seconds hands

• Blued steel or Polished steel lunar-cycle hand and fixed moon-phase index (4 o’clock)

Strap And Clasp

• Hand-stitched rolled-edge alligator leather strap made from a single piece of leather (115 x 75 mm, with a 20 mm buckle) – Various sizes available on request

• 18-carat white gold or Titanium double-blade length-adjustable folding clasp – Pin buckle available on request


• Hours, minutes, seconds, age and phases of the moon, power reserve on the back of the movement


Mechanical manual winding: Calibre FB-T.FC.L

Diameter: 37.30 mm

Thickness: 9.38 mm

Lines: 16 ½

Jewels: 55

Frequency: 21,600 vph (3 Hz)

Power reserve: 53 hours

Technical Characteristics

• Tourbillon with fusee-and-chain (constant-force) transmission

  Suspended fusée – differential winding system (Patent)

  Suspended barrel – Maltese cross stopwork system (Patent)

  Tourbillon with direct-drive seconds hand (Patent)

• Cam and feeler-spindle serving to display the age of the moon by means of a hand (Patent Pending)

• Variable-inertia balance wheel featuring four rhodium-plated nickel silver inertia blocks

• Balance spring with hand-crafted steel Phillips terminal curve

• Swiss lever escapement

• Three rhodium or black rhodium plated nickel silver half-bridges, fitted on stylised titanium pillars

• Power-reserve indications on the back of the movement, black-varnished and engraved with “0 to 1” and “Rés” inscriptions

• Hand finishing in keeping with the highest watchmaking standards

Components: 1,240 (including the chain)

Chain: 790 components

Length of the chain: 285 mm

Bridges: 18

Pillars: 6


Rotation: 1 /minute

Components: 67

Tourbillon carriage: Ø 16.55 mm (titanium)

Tourbillon carriage assembled with: 3 polished titanium pillars

Tourbillon carriage poised by: 2 inertia blocks in 18-carat gold

Balance wheel: Ø 12 mm in copper-beryllium

Officially chronometer-certified by the COSC

The prices for the Ferdinand Berthoud Chronomètre FB 1L are:

- CHF 250,000 for the Ref. FB 1L.4 Anthracite Ceramised Titanium version

- CHF 265,000 for the Ref. FB 1L.1 White Gold version

For more information visit Ferdinand Berthoud Online.