Germany’s A. Lange & Söhne has announced the fourth timepiece in its limited edition run of new releases to celebrate the 25th anniversary of 1994’s original Lange 1 (a new Lange 1 will be released each month until October). Following the classic-design Lange 1 Anniversary watch shown at SIHH in January, the Grand Lange 1 Moon Phase released in February, and last month’s Little Lange, the latest limited Lange 1 is the most complex we’ve seen so far. 
The Lange 1 Tourbillon Perpetual Calendar “25th Anniversary” watch follows the same design and material codes that its previously released brethren have established. The case is made of white gold, the asymmetrical dial argenté toned with blue accents and blued-steel hands, and production is limited to 25 total pieces. What differentiates the watch from its older siblings is the addition of a tourbillon hidden behind the dial and a perpetual calendar indication. This isn’t the first time that the Glashütte-based brand has released this combination within the greater Lange 1 family as it was first made available to the public in 2012. In fact, the new anniversary edition borrows the month indicator from that watch. In order to fit the various calendar indications on the dial, Lange developed a rotating ring around the periphery of the dial. The underside of this design features a circumferential contour with wave-shaped recesses. A spring-loaded sampler lever glides along this c...