Yema Builds Its First Moon Phase Around A Fixed Lume Moon With The Senans Grande Lune

Most moon phases use a printed disc beneath a window that move across the aperture as the Moon changes in the sky. The new Yema Senans Grande Lune does something a bit different and interesting. They don't move the moon at all It’s a domed moon made entirely of Super-LumiNova, fixed in place, and a thin bilobe disc rotates over it through the month to cover and reveal the glowing surface. The Senans is a new dress collection from the Morteau brand, and this is the first Yema with a moon phase.

The steel case is 38.5mm wide and 8.7mm thick, with a lug-to-lug of 46.4mm. That thickness doesn’t include the double-domed sapphire crystal, so expect it to wear a little taller. The stepped bezel is polished to a mirror. The case sides are brushed and the lugs bend down toward the wrist. There’s a sapphire caseback and you get 50 meters of water resistance.

The dials come in black, blue and gold. The moon sits in a large, asymmetric opening at 7 o’clock, its curved shape borrowed from the semicircular buildings of the Royal Saltworks at Arc-et-Senans, the 18th-century site near Morteau that gives the collection its name. The centre of the dial has a barleycorn pattern, stamped rather than engraved, which is expected at this price. Around it, the chapter ring has circular brushing and applied batons in two lengths, with the minute scale on a raised outer ring. The hands, indices and the ring around the centre are all lumed, as is the moon.

Inside is the calibre CMM.22, built on the CMM.20 that Yema developed with movement designer Olivier Mory. The moon phase costs only 1mm of height, taking the movement to 4.7mm thick, which is a real achievement for an automatic. The tungsten micro-rotor is set on ball bearings, the balance beats at 4Hz and power reserve is 70 hours. Through the caseback you’ll see bridges electroplated in dark grey, polished screws and purple jewels. You can have it on a leather strap or a mesh bracelet.

The Yema Senans Grande Lune is limited to 200 numbered examples of each dial. It's priced at €2,470 on leather and €2,570 on the mesh bracelet. See more on the Yema website.