In the Limelight: A. Lange & Söhne Datograph Up/Down Lumen

Ahead of next January’s Salon International de la Haute Horlogerie (SIHH), Germany’s A. Lange & Söhne, an SIHH mainstay, has unveiled the fourth addition to its Lumen series of heavily luminous-treated, transparent-dialed limited editions that began in 2010. The new Datograph Lumen features a flyback chronograph, precisely jumping minutes counter, power reserve indicator, and the emblematic outsize date display — all highlighted in darkness by the use of a luminous compound that glows a particularly pleasant and vibrant lime green.

A. Lange & Sohne Datograph_Lumen - glowing - soldier
The A. Lange & Söhne Datograph Lumen Up/Down features bright green luminous highlights on a semi-transparent dial.

The Datograph Lumen, which will be limited to just 200 pieces, has a platinum case measuring 41 mm in diameter. The sapphire dial has a special translucent coating that filters out most visible light except for the UV rays that serve to charge the luminous pigments on the various dial elements with energy. Thus, the darker the watch’s surroundings, the brighter its essential details glow against their background.

A. Lange & Sohne Datograph Lumen - light - front
The watch’s outsize date can be quickly adjusted with a pusher at 10 o’clock.

The rhodiumed hour and minute hands are filled with the light-activated pigment, and the central chronograph sweep-seconds hand is entirely covered with it. The off-centered subdials, one for running seconds, the other for tallying chronograph minutes, are coated with the substance and feature blued steel hands revolving above them. Surrounding the semi-transparent sapphire center of the dial are a minutes scale, subdivided into 1/5-second gradations, and a tachymeter scale, both of which also glow bright green in the dark. Also treated with the compound are the little arrow hand of the “Auf-Ab” (up-down) power reserve indicator at 6 o’clock and the two separate display disks of the outsize date, which recharge during the day as light passes through the dial.

A. Lange & Sohne Datograph_Lumen - dial CU - date
A tachymeter scale and minute rings occupy the periphery of the dial, whose special coating allows the glowing date disks to absorb light energy during the day.

The Datograph model, whose flyback chronograph mechanism allows uninterrupted timing of consecutive events with the push of a button at 4 o’clock, was launched by Lange in 1999 and the “Up/Down” version, with its dial-side power reserve display, joined the collection in 2012. When the 6 o’clock indicator’s arrow pointer enters the red area of its circular display, the owner knows it’s time to wind the watch’s movement to replenish it back to its full 60-hour power reserve. Like the Datograph Up/Down models that preceded it, the new Lumen version contains Lange’s in-house Caliber L951.7. This manual-wound movement is equipped with Lange’s proprietary cam-poised balance wheel, paired with a freely oscillating Lange hairspring, which beats at a frequency of 18,000 vph (2.5 hertz). In combination with the 300-marker minute scale, this allows the integrated stopwatch to perform time measurements accurate to a precision of 1/5- second. Like all Lange calibers, it is lavishly decorated in the classical Saxon style, with Glashütte ribbing on the plates and bridges, traditionally blued screws, and a hand-engraved balance cock.

A. Lange & Sohne Datograph Lumen - back
Lange’s Caliber L951.7 is visible through a sapphire exhibition caseback.

The A. Lange & Söhne Datograph Up/Down Lumen is offered on a hand-stitched, black alligator strap with a platinum pronged buckle. It will be priced at $100,500. Stay tuned to and our social media channels for more early looks at watches making their debut at SIHH 2019.

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