The German brand A. Lange & Söhne once again presents a translucent 'Lumen' version of one of its elite complicated mechanical models for collectors.
This is about the limited edition model with the reference 720.035FE - Lange 1 Tourbillon Perpetual Calendar 'Lumen'. The 'Lumen' models from A. Lange & Söhne feature a darkened sapphire dial, which serves two key functions.
Firstly, it allows one to admire the highly decorated in-house developed mechanical movement inside the watch. The company from Glashütte is not inclined to create skeletonized models, so the 'sub-dial view' through the translucent dial is a way to showcase the 'mechanical essence' of the watch while maintaining a classic and conservative front design.
Secondly, the translucent dial lets light through, which is necessary for charging the luminescent elements that are usually hidden under the dial on special discs. Thanks to the transparency effect, A. Lange & Söhne can apply luminescent material to elements like the large date window and the perpetual calendar wheel. In the Lange 1 Tourbillon Perpetual Calendar Lumen, the indicators under these windows change slowly enough that the light charging issue doesn't arise - the date or leap year indicator doesn't change often enough to lose illumination. Thus, the 'Lumen' concept is pleasant but not truly innovative in such limited models as this one.
To better understand why A. Lange & Söhne first created the Lumen concept, it's worth returning to 2012.
The History of the Lumen Concept: Zeitwerk Lume 2012
In 2012, the company released the first Lumen model - A. Lange & Söhne Zeitwerk Lume. These watches with a digital mechanical display initially lacked luminescent coating, and collectors challenged Lange to find a solution. The problem was that the hour and minute numbers were hidden under the dial and couldn't charge enough light to glow in the dark when appearing in the windows. The solution was to create a transparency effect on the front so that light could penetrate and charge the luminescent discs. Since the glow was necessary for the time display system, it became an innovation and was recognized by Lange fans. Over the years, the Saxon company has released several other Lumen models, but none were as utilitarian as the original Zeitwerk Lumen, since most Lange watches are equipped with traditional hands that can easily be covered with luminescent material.
In the Lange 1 Tourbillon Perpetual Calendar model, the important hands are covered with lume and do not require a transparent dial. While having more luminescent material on the dial and discs adds visual effect, it doesn't carry deep functional significance. For me, this is somewhat disappointing, as I appreciate A. Lange & Söhne for its constant pursuit of perfection and masterful hand finishing. The Lumen version for the Lange 1 Tourbillon Perpetual Calendar is more perceived as a spectacular accessory aimed at having 'watchmaker friends appreciate the dial's glow'. However, this is an important marketing move in our time. Simultaneously with the release of these watches at Watches & Wonders 2026, sister brand IWC presented the Big Pilot’s Ceralume with a fully luminous case.
Limited Edition Lange 1 Tourbillon Perpetual Calendar
The limited edition with reference 720.035FE continues the traditions of the elite Lange 1 family - a model with a traditional asymmetrical dial, first introduced in the mid-1990s with the company's relaunch. The Lange 1 became a signature design with a multifunctional dial, where the main time is displayed on an off-center subdial, and the large double disc date takes center stage. This limited series includes only 50 pieces with a 950 platinum case measuring 41.9 mm in diameter and 13 mm in thickness, and water resistance up to 30 meters. An elegant black alligator leather strap is attached to the case.
Few A. Lange & Söhne watches feature a tourbillon, and this model is one of them. The company does not always display the tourbillon openly. The first tourbillons, for example from the Cabaret collection, were hidden under the dial. Later models with open tourbillons appeared. In the Lange 1 Tourbillon Perpetual Calendar, the dial features the word 'Tourbillon', yet the regulatory mechanism is not visible from the front. The tourbillon is practically concealed under the automatic winding system, which does not diminish its technical value. Special attention is deserved by the diamond (not ruby) capstone in the tourbillon mechanism used by Lange.
Caliber L225.1 Automatic Movement
Inside the watch is the in-house automatic caliber L225.1. A tourbillon with automatic winding and a perpetual calendar is a rare combination, and considering Lange's craftsmanship, the movement becomes even more special. The operating frequency is 3 Hz, with a power reserve of 50 hours.
The automatic winding rotor is crafted from solid 18-carat white gold, which beautifully contrasts with the German silver bridges. The combination of gold hues, blue steel screws, and red ruby stones creates an impressive composition, complemented by hand finishing and polishing of all surfaces.
Features of the Perpetual Calendar Dial
As a perpetual calendar, the dial of the Lange 1 Tourbillon Perpetual Calendar displays a substantial amount of information in an elegant and convenient form. At the '6 o'clock' position is a small leap year window, which transitions into a hand indicating the current month along the dial's periphery. The seconds hand is combined with the moon phase indicator. Note the moon phase disc with luminescent coating around polished silver moon figures - this is a striking design solution. A retrograde hand is used to indicate the day of the week, and the signature double digital date window remains a prominent element.
Despite the dial's translucency, the watch's readability remains high due to the well-visible hour markers and hands. Special thanks to Lange for the convenient tool for setting the perpetual calendar, available on the model's official website.
Conclusion: A Limited Series for Connoisseurs of Mechanics and Design
While this model is not the most compact or utilitarian in A. Lange & Söhne's collection, it represents an impressive limited edition with complications and an interesting visual effect that connoisseurs and collectors will appreciate.
The Lumen concept deserves attention, but in my opinion, it should be applied mainly in models where disc light charging is truly necessary, such as in Zeitwerk. An interesting option could be the Richard Lange Lumen. The bold and stylish design in a platinum-black color scheme will find its fans among the 50 lucky owners of this limited series from Glashütte. The price of the 720.035FE A. Lange & Söhne Tourbillon Perpetual Calendar Lumen is 550,000 euros.