Today, A. Lange & Söhne announced the Grand Lange 1 “Lumen.” The Lumen, not to be confused with the Grand Lange 1 Luminous, has a cool smoked sapphire crystal dial like the extremely popular Zeitwerk Luminous.
Last year, A. Lange & Söhne introduced a redesigned Grand Lange 1 with a new movement and a non-overlapping dial. The limited Grand Lange 1 Lumen features the new caliber, and its semi-transparent dial is non-overlapping like the iconic Lange 1.
Previously, the complex mechanism responsible for this unprecedented date display format remained hidden beneath the solid-silver dial. Now, with the semi-transparent sapphire crystal dial, you can see the date mechanism — and it glows in the dark. Additionally, the time and power reserve glow in the dark as well. The outer ring and the hour, minute and small second dials are made of blackened silver.
“The technical challenge encountered during the development of the Lumen, was to ensure maximum luminosity for the date display, even immediately after the daily switching operation. Lange’s product developers solved this issue in an exceptional way.
While the tens cross was coated with a white luminous compound and subsequently imprinted with black numerals, the units disc consists of transparent glass imprinted with black numerals and rotates before a luminous background.
The sapphire crystal sections of the dial are treated with a special coating that blocks most of the visible spectrum of light. For the invisible UV light spectrum, however, the coating does not represent a barrier. Therefore, UV radiation can pass through to the luminous surfaces of the outsize date unhindered.
This produces an interesting side effect: the date platform with its manually applied perlage, normally seen only by the watch- maker during the assembly process, is now visible to the owner as well. The small, overlapping circular graining produced by hand using a rotating abrasive peg is normally concealed underneath the dial.”