The new version of the iconic Golden Bridge now displays a case fashioned from black ceramic.
Fashioning an all-ceramic watch case is a complex exercise that involves injecting crystals into a mold at around 980-bar pressure. The first challenge involves ensuring that the material is uniformly spread so as to avoid any roughness in the resulting surface texture. The next step is a 30-second firing in a furnace heated to 160°C in order to harden the still porous material. This tricky phase causes the ceramic to shrink by about one-third of its volume in order to reach its final 34 x 51 mm size. This task calls for complete mastery of the firing time, since a few seconds too many could entail excessive shrinkage that would make the case too small to accommodate the caliber.
The baguette movement stretches along the length of the tonneau-shaped case. This mechanism first created in 1980 quickly established itself as a Swiss watch industry icon masterfully meeting the energy transmission challenge implied by its vertical-axis construction. The pure ceramic Golden Bridge even lines up the crown at 6 o’clock as if to form an extension of its hand-wound CO 113 movement. Its slipping-spring winding system avoids forcing the mechanism, while a specific coupling clutch has been developed to separate winding from time-setting by means of an ingenious architecture in which the wheels and pinions are mounted between the mainplate and the bridge. Rather than a classic index- or regulator-type system, the caliber is equipped with a variable-inertia balance guaranteeing excellent long-term accuracy. Beating at the frequency of 4 Hz (28,800 vibrations per hour) and endowed with a 40-hour power reserve, the movement features two pillars visible on the bridges and ensuring enhanced resistance and rigidity.
Staged within its black ceramic case framed by four sapphire crystals forming the upper glass, back and sides, the baguette movement invites observers to enjoy a 360° immersion into its linear mechanism. The 5N 18K red gold upper bridge bears the hand-engraved Corum signature, surrounded by a slender scrolling motif depicting the three types of fern that grown in the forests of La Chaux-de-Fonds, the region where the Golden Bridge sprang to life. The red gold mainplate is also adorned with hand engravings embodying the finest watchmaking traditions. Standing out against the movement, the openworked baton-type hands appear to revel in the absence of a dial. An alligator leather strap fitted with a black PVD-coated pin buckle sets the finishing touch.
