Limited to 50 pieces and presented at Watches & Wonders in April 2026, the Lange 1 Tourbillon Perpetual Calendar 'Lumen' 720.035FE brings A. Lange & Söhne's luminescent treatment to the most complicated watch in the Lange 1 family. It is the seventh model in the Lumen series, which began in 2010 with a luminescent Zeitwerk and has since included the Grand Lange 1, the Grand Lange 1 Moon Phase, the Datograph Up/Down, a Zeitwerk in Honeygold and the Datograph Perpetual Tourbillon. Like its predecessors, it pairs a dial of semi-transparent sapphire with luminescent displays that glow after dark, but it takes the idea further than any of them: every calendar indication shines, from the outsize date to the ring of months around the edge, and the moon is outlined in luminescent material for the first time in the series. Behind that dial sits an entirely redesigned self-winding movement combining a perpetual calendar with a tourbillon and stop-seconds, all in a Platinum case. Recent Lumen editions have been made in smaller numbers than the early ones, and this one, at 50 pieces, places the series firmly among the manufacture's most demanding watches.
The Platinum case is polished, 41.9 mm in diameter and 13 mm high, and its bright surfaces contrast with the dark face and the hand-stitched black alligator strap, which closes with a Platinum deployant buckle. The dial is the defining element. It is cut from sapphire crystal and given a special coating that holds back most visible light, so it reads as smoky and dark, while allowing ultraviolet light through to charge the luminescent pigments placed beneath the displays; Lange has protected this process by patent since 2013, and it can be recharged indefinitely. In daylight the semi-transparency reveals parts of the movement beneath: grained plates, sun-brushed bridges, satin-finished levers and wheels with circular graining, all with edges bevelled by hand, so the calendar mechanism becomes part of the design. Rhodium-plated gold hands and white hour markers keep the time legible against the dark ground, and the familiar Lange 1 arrangement remains intact, with the outsize date, the retrograde day of the week, the leap-year window and the month ring set around the off-centre time display. On the dial itself, only a small engraving near 12 o'clock hints at the tourbillon on the other side.
When the light fades the dial changes character. The outsize date, the retrograde day, the month ring and the leap-year indication all glow, the larger elements with an even intensity and the hands, markers and moon with a softer light, giving a graded effect rather than the flat brightness of an ordinary luminescent dial. The moon phase is combined with a day and night disc that turns once in 24 hours: by day the moon crosses a plain sky, by night it passes in front of luminescent stars, and Lange states that the display deviates by only one day in 122.6 years. Underneath, the perpetual calendar works on the principle Lange devised for the Lange 1 in 2012. A wave-shaped contour inside the month ring, read by a spring-loaded lever, tells the mechanism how long each month is, and a second arm of the same lever consults a cam beneath the leap-year display to settle February. Because the ring must leap 30 degrees at once, the switching energy is stored over the day in two separate springs, one for the daily changes and one for the monthly step, and released in an instant without disturbing the balance. Correctors adjust the displays individually or together, and the calendar runs unattended until 1 March 2100.
The movement is not an adaptation of the earlier tourbillon perpetual calendar but a completely redesigned self-winding movement, because a semi-transparent dial exposes surfaces that were previously hidden and must now be laid out and finished to be seen. It has 685 parts, 74 jewels and six gold chatons, an eccentric balance with a hairspring made by Lange, and a central White Gold rotor with a Platinum outer mass that provides 50 hours of running time. Through the sapphire caseback, the minute tourbillon turns once every 60 seconds. It carries Lange's stop-seconds system, patented in 2008, in which a V-shaped spring presses against the balance when the crown is pulled, holding it wherever the cage stands and letting it restart at once. The tourbillon bridge and the intermediate-wheel bridge are skeletonised steel with black-polished surfaces, engraved by hand with stars and a shooting star that answer the glowing sky on the dial, and the cage is capped by a diamond endstone in a screwed gold chaton, a detail drawn from Lange's highest-grade historic pocket watches. The earlier Lange 1 Tourbillon Perpetual Calendar of 2012 introduced the peripheral month ring and kept its tourbillon hidden from the front; this Lumen edition is the first version that lets the wearer look into the calendar mechanism from the dial side.
The 720.035FE is aimed at collectors for whom the Lumen series has become a collecting theme of its own, and at those who want the Lange 1 grand complication in its most unusual form. With 50 pieces, it is one of the smallest Lange 1 editions of recent years and, after the Datograph Perpetual Tourbillon of 2024, the second Lumen watch to combine a perpetual calendar and a tourbillon. It rewards attention at every hour: in daylight the dial reveals the calendar mechanism beneath its tinted sapphire, at night the displays glow in graded tones with a starry sky behind the moon, and on the back the black-polished bridges and engraved stars frame the tourbillon. The Platinum case and black alligator strap keep the presentation sober, so that the dial provides all the drama. For owners of the regular Lange 1 Tourbillon Perpetual Calendar, it offers a different reading of the same idea, one in which the hidden becomes visible. For collectors of Lange's earlier Lumen pieces, it is the edition that brings the series to the most complex model in the Lange 1 family, and the one in which the luminescent concept reaches its fullest expression so far.
