The Corum Golden Bridge has gotten a makeover in Black Ceramic. Originally, the Golden Bridge was made only in precious metals i.e. 18kt rose, yellow, or white gold but last year Corum decided to offer this revolutionary timepiece in black ceramic. Ceramic is both lighter and stronger than stainless steel. Ceramic also has the distinction as being virtually scratch proof. In reality, only diamond, which is the hardest mineral in the world can scratch ceramic.
The Golden Bridge’s claim to fame is its unconventional yet equally stunning bridge inspired baguette shaped movement made completely from 18kt rose gold. On this black ceramic creation, the movement stands out wonderfully. The wearer is given a 360° panoramic view of the movement by the four sapphire crystals boxing it.
The watch is made in tonneau shape with dimensions of 34mm across and 51mm top to bottom. The main crown is crafted from 18kt rose gold and can be found at the 6 position, where it maintains the perfect case symmetry of the watch. This model is outfitted with a large square scaled black alligator leather strap.
Ceramic cases are notoriously difficult to manufacture. First of all, the crystals are injected into a mold at a very high pressure of 980 bars. Then they are spread evenly to avoid roughness in the finished product. It is then heated to 160° in a furnace for 30 seconds to harden the ceramic. This is the most important phase as it also shrinks by about 33%. If fired for too long the case will shrink too much and will be able to house the movement.
Powering this model is the hand wound caliber CO 113. This movement features a Slipping-Spring winding mechanism, which allows the mainspring to not be over-wound. To accommodate the vertical alignment of the movement design, Corum has developed a special coupling clutch to differentiate the winding and the time setting functions. This caliber is also equipped with a variable inertia balance that endures accuracy over a long period of time. The balance wheel vibrates at 28,800 alternations per hour and it carries a 40 hour power reserve.