A. Lange & Söhne Zeitwerk Yellow Gold 140.021

Lange introduced the Zeitwerk in 2009, and it won the Aiguille d'Or at the Grand Prix d'Horlogerie de Genève that November. The display takes its cue from the stage clock of the Semper Opera House in Dresden, which Johann Gutkaes built with help from his son-in-law Ferdinand Adolph Lange. Inside is the hand-wound calibre L043.1: a constant-force remontoir releases energy every 60 seconds to advance the three numeral discs, a power-reserve display sits at 12, and the watch runs for 36 hours.

The case measures 41.9 by 12.6 mm and takes a 20 mm strap. The same case comes in platinum with a silver dial (140.025, limited to 200 pieces), in white gold with a black dial (140.029) and in pink gold with a silver dial (140.032). The Zeitwerk Striking Time and Minute Repeater use a 44.2 mm case, and the Zeitwerk Date of 2019 adds a date ring in the same larger size.