The 'Lumen' series launched by A. Lange & Söhne in 2010 has been updated with a new model: the Datograph Up/Down, the fourth in this series to feature a special semi-transparent sapphire-glass dial coating that filters out most visible light, with the exception of the UV rays needed to charge the luminous pigments with energy. The darker the environment, the greater the contrast of the indications against the dark background.
This is a 200-piece limited edition of this famous chronograph with flyback function, "jumping exactly" minute counter and power reserve display. Thanks to the semi-transparent dial and the fluorescent substance, all indications light up in the darkness in a shade of green. The hour and minute hands are equipped with a luminescent substance and the central chronograph hand is completely coated with it. The seconds and minute counter hands in burnished steel rotate on the auxiliary dials below, which are also luminescent. Similarly, the dial ring with the minute scale divided into fifths of a second, the concentric tachymeter scale and the arrow indicating the power reserve glow a brilliant green. But the greatest impact is achieved by the luminous Big Date: the two separate displays light up in the darkness thanks to the tens cross coated with a luminescent substance and the units disc with black numerals in transparent glass rotating against a luminous background. Both elements, located below the dial, must be exposed to daylight in order to be charged. This is made possible by the semi-transparent dial, which gives the watch its unmistakable design during the day. Its coating makes it possible to observe the change of the Big Date in detail both in daylight and at midnight.
The case back reveals the hand-wound L951.7 calibre, housed in a platinum case.
