The name ‘Sidéral’, meaning ‘related to the stars’ and also a system of timekeeping that uses not the Sun but the fixed position of stars as a reference, refers to the notion of constant motion of the tourbillon much like the planetary systems, and therefore a link to astronomy. The name also finds expression in the aventurine dial, which is reminiscent of twinkling stars. 

The flying tourbillon, with a striking design, is at the heart of this timepiece - in fact the entire movement of the watch is built around it, and its proportions guide the proportions of the watch. Unlike a traditional tourbillon, the flying tourbillon’s cage is supported only by its lower bridge, without an upper bar. It is thus held solely from below. The lower bridge in this model is made of sapphire glass, making it look invisible. Apart from this, the point of contact between the gears and the carriage is offset from the tourbillon cutout, leaving it hidden by the dial, creating a levitating look. The tourbillon is raised by 0.9 mm above the aventurine enamel dial to accentuate the depth of the device furthering in on the sensation of floating in the void like planets floating in space. 

Around the hour ring and tourbillon, the 38 mm dial looks like a galaxy. To achieve that, a first for Breguet, this model features a unique aventurine enamel grand feu dial. To achieve this, a glass is shattered into powder with slightly larger grains than the traditional enamel powder. Breguet has used five layers of aventurine powder, each layer is meticulously fired in the kiln at over 800 degrees Celsius. There are copper particles randomly sprinkled on the dial, making it look like a galaxy of stars. Taking inspiration from the celestial method of timekeeping, the dial looks like a deep night sky, sparkling with stars. All the dials, of this 50-pieces limited edition timepiece, are assembled by hand making every model precisely unique. The dial comprises a gold base with a raised rim and a gold tourbillon bezel. The raised rim and the tourbillon bezel form raised walls around the dial, allowing the aventurine enamel to be carefully cured throughout the enamelling process. Contrasting with the dial, there are “Breguet” and “Tourbillon” appliques placed at 9 o’clock and 3 o’clock, respectively. 

The watch houses the hand-wound Calibre 187M1 with a power reserve of 50 hours. Each piece is individually numbered from 1/50 to 50/50 on the back. The watch is finished on a navy blue alligator strap fastened to welded lugs and comes in a special 250th Anniversary Edition box in red leather. 

Images: Courtesy Brand