A. Lange & Sohne Grand Lange 1 Moonphase Yellow Gold (139.021)

A. Lange & Söhne's latest masterpiece of haute horlogerie unites two classic complications with the expressive LANGE 1 style. Thanks to an ingenious arrangement of the calendar displays around the time indication, the LANGE 1 TOURBILLON PERPETUAL CALENDAR presents an abundance of information in a superbly legible layout.
The off-centre configuration of the LANGE 1 dial offers ideal prerequisites for the integration of a perpetual calendar. This is because the calendar displays can be neatly positioned outside the hour and minute circle without compromising the readability of the time indication in any way. On the face of the LANGE 1 TOURBILLON PERPETUAL CALENDAR, the integration of the calendar is so harmoniously balanced that the complication suggested by its name is not obvious. Only a modest inscription at 12 o'clock refers to the tourbillon with the patented stop-seconds mechanism. The equilibrium of the dial provides no further clues regarding the technical complexity and immense engineering effort behind the development of this horological magnum opus. The tenth masterpiece to be added to A. Lange & Söhne's most famous watch family embodies fundamentally new mechanical solutions.

To create the prerequisites for integrating a calendar in the dial architecture of the LANGE 1, the manufactory's calibre designers devised the very first rotating peripheral month ring ever implemented in a wristwatch. The underside of the ring has recesses of different depths for the respective durations of each month and features an innovative sampling mechanism. This one-of-a-kind design has been registered for patent.
All displays of the perpetual calendar - the outsize date, the retrograde day, the month ring, the aperture leap year, and the moon-phase indication - switch instantaneously and thus always deliver unambiguous readings. The mechanism is designed such that it must only be advanced by one day on March 1st of the secular year 2100. And the moon-phase display will even run true for 122 years before it needs to be corrected by one day. Corrections are easy to perform with recessed push pieces that allow the calendar indications to be advanced individually or collectively.

One objective in the development of the LANGE 1 TOURBILLON PERPETUAL CALENDAR was that nothing should obstruct the legibility of the indications on the dial. The determination to achieve it came at a price: the dial has no aperture for the tourbillon. But the refined complication can be admired in all its technical immaculacy through the sapphire-crystal caseback. Here the filigreed cage rotates about its axis once a minute to eliminate the influence of gravity on the balance wheel and its eccentric poising weights. Combined with the proprietary Lange balance spring, it assures an extremely high degree of rate accuracy. Both components are exactly matched to one another to achieve optimised precision at the movement's rated frequency of 21,600 semi-oscillations per hour. The patented stop-seconds mechanism makes it possible to instantly block the balance inside the tourbillon cage at any time by pulling the crown, so the watch can be set to one-second accuracy.

The high winding efficiency of the new automatic calibre L082.1 is attained with a heavy central rotor whose middle segment with the embossed A. Lange & Söhne signature is made of 21-carat gold. The platinum centrifugal mass on the outer periphery of the rotor has an even higher density than gold, so it imparts extra momentum to the winding process. Thus, even the slightest motion of the wrist is converted into winding energy. The result: the maximum power reserve of 50 hours is available after a very short time on the wrist.
The movement is endowed with many iconic Lange-style quality hallmarks such as the movement parts lavishly decorated by hand, the free-hand engravings on the tourbillon and intermediate-wheel cocks, and the four gold chatons secured to the plate with thermally blued screws. The upper part of the tourbillon cage receives what is no doubt the most sophisticated and time-consuming type of finissage: It is called black polish, which on this tiny but elaborately convoluted part can require up to five days of work. The crowning touch of Lange watchmaking artistry is represented by the flawless diamond endstone which serves as a bearing for the tourbillon. It is a reminiscence of historic Lange pocket watches that belonged to the high-end "1A" category.
The so far most complicated member of the LANGE 1 family is available in a pink gold or platinum case with a diameter of 41.9 millimetres. The strict limitation of the platinum version to an edition of 100 watches underscores the exclusivity of this extraordinary timekeeping instrument.