In horology, a complication is any feature of a timepiece beyond the display of hours, minutes and seconds. A timepiece indicating only hours, minutes and seconds is known as a simple movement. Common complications include date or day-of-the-week indicators, alarms, chronographs (stopwatches), and automatic winding mechanisms. Complications may be found in any clock, but they are most notable in mechanical watches where the small size makes them difficult to design and assemble. A typical date-display chronograph may have up to 250 parts, while a particularly complex watch may have a thousand or more parts. Watches with several complications are referred to as grandes complications.

Types

Timing

Many of these complications can result in watch defects, often due to watch owners manipulating mechanisms without an instruction manual, or disregarding "no-set-periods", time periods when no setting should be attempted, such as a certain phase before midnight when a watch with a date complication is already in the process of internally shifting discs.

Mechanical

Astronomical

Striking

Non-horological

By some definitions, a display on a watch may be a complication even if it is unrelated to time-telling. Some horologists discount non-horological features (even those tangential to timekeeping such as winding limitations mechanisms or power reserves) as being true complications. Examples include:

Grand(e) complications

A grand(e) complication is a watch with several complications, the most complex achievements of haute horlogerie, or fine watchmaking. Although there is no official definition, one common criterion is that a watch contain at least one (visible) timing complication, one astronomical complication, and one striking complication. Ultra-complicated watches are produced in strictly limited numbers, with some built as unique instruments. Some watchmaking companies known for making ultra-complicated watches are Breguet, Patek Philippe, and Vacheron Constantin. The initial ultra-complicated watches appeared due to watchmakers' ambitious attempts to unite a great number of functions in a case of a single timepiece. The mechanical clocks with a wide range of functions, including astronomical indications, suggested ideas to the developers of the first pocket watches. As a result, as early as in the 16th century, the horology world witnessed the appearance of numerous complicated and even ultra-complicated watches. As of November 2018, the top four most complicated mechanical watches ever created are manufactured by Vacheron Constantin and Patek Philippe, respectively. In particular, the Patek Philippe Henry Graves Supercomplication currently holds the title of the second most expensive watch ever sold at auction, with a final price of US$24 million (23,237,000 CHF [Swiss francs]) sold in Geneva on November 11, 2014. Two Patek Philippe Calibre 89 also currently rank among the top 10 most expensive watches ever sold at auction, with final prices over 5 million US dollars. The Franck Muller Aeternitas Mega 4 is the world's most complicated wristwatch. It has 36 complications, 25 of them visible, 1483 components and 1000-year calendar. Blancpain is famous for being the creator of one of the most complicated mechanical watches ever made, the Blancpain 1735, which is a true grand complication (Tourbillon, minute repeater, perpetual calendar, split chrono), a limited edition of 30 pieces only, production of just one piece per year. The Hybris Mechanica Grande Sonnerie is the world's second most complicated wristwatch. Powered by the Jaeger LeCoultre Calibre 182 movement, with 27 complications and over 1300 parts. The movement is housed in a 44mm by 15mm 18k white gold case.

Use in smartwatches

In smartwatches, complications are features other than time display, implemented in software.

[Smartwatch with the following complications:

Heart rate with sparkline; Moon phase; date; weather; sunrise/sunset. | upload.wikimedia.org/wikipedia/commons/9/95/Garmin///Instinct///2s.jpg]