The Reason

An hourly passing strike with both the going train and striking train driven from the same barrel and wound by the same automatic mechanism.

(Launched in 2010) 

Functions: offset minutes & hours with passing strike, sounding on the hour by two hammers striking two gongs 3 times. On/off button at 1 o’clock, the diamond between the hammers indicates the passing strike is activated, when it is replaced by a white zone it is inactive.

Winding automatic Power reserve 65 hours Calibre 78S0 Jewels 60 Balance-spring Silicon Frequency 3Hz Number of components 331 Case metal white gold Diamonds x 30, 2.93cts Back and front Sapphire Height 40,05mm Width 30,4mm Height 38,45mm Thickness 11,6mm Water-resistant 30m

Each Breguet ‘Reine de Naples’ watch has a unique serial number which is found both on the dial and case back, then recorded in the company archives.

The profile of the case continues the overall design aesthetics of the egg form but flattened for ergonomics.

The case back removed showing the complete calibre which follows the same shape as the case. The blued screws in the case centre hold in place the bezel.

The bezel removed.

The mother of pearl dial with white gold base and name/number plaque. The dial below has not yet had the reference number, married to the case, added. The final image in the group shows the dial in its protective transportation/storage box, used before casing.

The blued, steel hands shown below are received before the initial assembly in paper sheaths.

The rotor weight, gongs and dial removed showing an unobstructed view of the calibre form and bird shaped and engraved bridges.

The rotor weight is hand engraved and made from 22carat gold before being rhodium treated.

The gongs upon which the hammers strike. The black elastics which are wound around the gongs are a security to avoid any unwanted sounds when the watch is worn and receives any form of shock causing the gongs to knock together.

The balance assembly removed. The white bearing around the centre axe for the rotor weight is made in ceramic, those in red are made from synthetic ruby. They can be made in any colour or even transparent, but are made red for both traditional reasons as well as being easily seen and manipulated when they are fitted or replaced.

The barrel assembly which both drives the going train leading to the escapement and telling the time, as well powers the passing strike mechanism.

The hardened steel hammers which strike the two gongs. Above them a lever set with a diamond and white zone which indicates whether the passing strike is activated or not, aligning with the hole in the centre of the dial between the hammers.

The fully assembled central bridge block, including at the bottom the going train and at the top the automatic wheels and the first part of the passing strike train.

The bridges removed from the main-plate showing in the upper section the striking mechanism. The circular racks act on the hammer trips activating the hammers. The screws with two slots are eccentric plugs used for adjusting the distance the hammers can fall from the gongs. The large screw with three slots is tightened anti-clockwise. The jewelled lever is part of the selection devise.


The empty main-plate and diverse bridges and components.

The dismantled case

Close ups of the pusher and winding crown. In the base of the selection pusher under the stone is the form of a note in relief.


With both the going train and the striking train driven from the same barrel and wound by the same automatic mechanism the design limits the volume required for conventional ‘sonneries’, practical in a relatively small ladies watch. The aesthetics are simple although the theory behind the calibre complex, including assuring the time-side of the watch continues for the published power-reserve once the power reserve for the passing strike becomes in efficient to drive the hammers.

Diverse images of the assembled watch.

A short film with sound illustrating the hammers hitting the gongs on the hour.

To learn more about Breguet