Appearing at 9 o'clock, the three main escapement organs – the balance-wheel, pallet-lever and escape-wheel – are thus individualised, distinct and prominent. This ample space dedicated to the regulating organ enables its operation to be admired in full, and the cylindrical balance-spring to be seen beating throughout the three-day power reserve, including through a large water-resistant porthole created in the case middle.
One-of-a-kind anniversary model
The Chronomètre FB 3SPC draws its stylistic, technical and aesthetic inspiration from a rare and exceptional creation, the No. 26 decimal watch, made in 1793 by Louis Berthoud. Calibre FB-SPC is based on a cylindrical balance-spring, a rare watchmaking speciality. It is the only one of its kind to satisfy the chronometric (precision timekeeping) criteria of the COSC: ISO 3159 certification made possible only by the precision adjustments performed by the Manufacture's watchmakers.
For its second participation in Only Watch, Chronométrie Ferdinand Berthoud is offering a new version of the FB3 collection: a one-of-a-kind model presented in a patinated bronze case, a tribute to the ‘Master Watchmaker’ title granted to Ferdinand Berthoud just 270 years ago.
features
Its round case recalls the curves of pocket watches from the early 19th century, such as the decimal watch No. 26, made in 1793 by Louis Berthoud and now on display within the Chronométrie Ferdinand Berthoud heritage collection in Fleurier.
Several months of preparation and testing were necessary to achieve the patinated bronze case of the Chronomètre FB 3 Only Watch. The colour and nuances are unprecedented and evoke to the discerning gaze the patina that naturally develops on the copper alloys of the precision and navigation instruments supplied by Ferdinand Berthoud during the 18th century.
Specifications

Case & Dial
- Thickness : 9.43 mm
Case
- Material : Case in brown patinated bronze
- Case Type : Round with a transparent sapphire ‘porthole’ at 9 o’clock
- Diameter : 42.30 mm
- Thickness : 9.43 mm
- Water resistance : 30 m
- Glass : Domed sapphire crystal glareproofed on both sides
- Case-back : Exhibition back in sandblasted titanium fitted with a glareproofed sapphire crystal pane
- Crown type : Brown patinated bronze with FB logo in titanium
Movement
- Calibre : FB-SPC
- Type Of Movement : Mechanical with cylindrical balance-spring
- Type Of Winding : Hand-wound
- Diameter : 34 mm
- Тhickness : 6.84 mm
- Lines : 15'''
- Number of jewels : 47
- Frequency : 21,600 vph (3Hz)
- Power reserve : 72 hours
- Number of components : 230
- Certification : Chronometer-certified by the COSC
Dial and Hands
- Dial : Sandblasted nickel silver and 2N gilded
- Eggshell-coloured inner bezel ring for the hours and minutes and seconds subdial, in sandblasted silver-toned brass
- Facetted and skeletonised and open-tipped hours and minutes hands in 18-carat gold with blue CVD treatment
- Seconds hand with counterweight in 18-carat gold with blue CVD treatement
- Arrow-shaped power-reserve hand in 18-carat gold with blue CVD treatement
Functions and Display
- Central display of the hours and minutes
- Seconds at 6 o’clock
- Power reserve at 2'o'clock
Strap and Buckle
- Strap : Dark green alligator leather strap and chestnut brown aged calfskin leather strap
- Buckle : 18 mm pin buckle in sandblasted titanium