The dial is considered the face of a watch. In mechanical wristwatches, it is usually made of coated metal—sometimes precious metal—and is often decorated with ornamental polishing. The information provided by a dial is as varied as the watch models themselves, and ranges from the single-hand watch without any printed or applied divisions (a minimal watch), to the 12-hour variant with or without a minute track, to dials with several division units (subdials) and additional complication displays. The dials of NOMOS watches usually have a sub-seconds dial and, in the case of models with complications, different and sometimes patented forms of displaying the date, power reserve, a second time zone or world time.
The fact that a mechanical clock has a dial divided into twelve hours is not self-evident. The first mechanical clocks with a gear train, which appeared in Europe around the year 1300, did not have a visible display, but rather were tower clocks that informed people in the surrounding area about the progress of time by chiming bells. The first clock faces were also so-called "big clocks", which had a marker for all 24 hours of a day. "Small clocks" with only twelve divisions became widespread only with the modern custom of considering the calendar day as a unit of daytime and nighttime. Such a calendar day comprises of twelve hours times two, even if the actual "time of day" might vary between eight and 16 hours, depending on the geographical location and season.
The time, of course! However, this can vary by accuracy. There are dials with only an hour index, with Arabic or Roman numerals, or with placeholders such as dots or dashes. When Roman numerals are used (for example, in the NOMOS model Ludwig), it is peculiarity of watchmaking tradition that IIII is written instead of IV. Perhaps because it appears more harmonious as an optical counterpart to the VIII. When Roman and Arabic numerals are mixed, as in the NOMOS model Club Campus, it's called a "California dial". Usually, the Roman numerals are placed in the upper half of the dial, but Club Campus has turned this around and is an intrepid, spontaneous watch. In addition to the hour indexes, many dials show the minutes, usually as dashes or dots, sometimes with Arabic numerals above the hour markings—or as a so-called "chemin de fer", a railroad line: a string of track-like boxes at the edge of the dial. This also serves as a reminder of the importance the avent of the railroad had for the synchronization of time zones and the development of the watch.
Other elements of a dial are, as mentioned, complication displays—whereby the tourbillon, where there is nothing to display, can often be seen through a corresponding window in the dial itself. More extensive recesses, called skeletonization, can also occur; up to the complete absence of a dial in the mechanical watch, where one then sees the hands circling directly above the movement. Representation is also part of the task of the dial. Not only through the aesthetic design, but also through the naming of the manufacturer, the designation of special features of the movement (such as "neomatik" on the NOMOS automatic watches with the NOMOS swing system) or a reference to the origin of the watch. Like "Swiss made" timepieces, the "Glashütte" designation of origin is protected by law in Europe and is subject to strict regulations.