Every distinguished timepiece is a meticulously assembled creation, where each component plays a vital role in both form and function. An aperture, for instance, is a small window on the dial that reveals indications such as the date, day, or moon phase, as seen in the classic Rolex Submariner Date, a model that commanded £9,450 in a 2021 sale. Surrounding the dial, the bezel frames the watch face, often serving a functional purpose, exemplified by the distinctive 24-hour bezel of the Rolex GMT-Master, a variant originally conceived for aviators navigating multiple time zones. The case acts as the protective enclosure for the watch's intricate internal mechanisms; the robust casing of the Audemars Piguet Royal Oak Offshore, which realized HKD 302,400 in a 2022 sale, underscores its wearability. The crown is the external control used to set the time and, in mechanical watches, to wind the mainspring; the Cartier Ballon Bleu is instantly recognizable by its unique blue sapphire cabochon crown, appearing to float within a protective arch. The dial, often referred to as the face, is where time and other information are elegantly displayed, with the Audemars Piguet Royal Oak showcasing a harmonious blend of legibility and aesthetic appeal. The escapement is the regulating heart of a mechanical watch, governing its timekeeping precision; the Omega DeVille, for example, utilized the innovative co-axial escapement. The hands are the indicators that point to the time or other data on the dial, such as the broad-arrow hands of the Omega Speedmaster, designed for optimal legibility. Indexes are the markings—be they numerals, shapes, or Roman numerals—that the hands reference to indicate time; Breguet's Reference 5140 exemplifies the brand's renowned attention to these carefully considered details. Finally, the lugs, an integral part of the case, secure the watch strap or bracelet, contributing significantly to the overall design harmony, as demonstrated by the Patek Philippe Calatrava.

Beyond basic timekeeping, complications introduce additional functions that showcase the pinnacle of horological ingenuity. A watch featuring at least three distinct advanced functions is often termed a grand complication. The annual calendar displays the day, date, and month, requiring manual adjustment only once a year for February's shorter duration, a feature seamlessly integrated into models like the Patek Philippe Nautilus alongside moon phases. A chronograph functions as a sophisticated stopwatch, capable of measuring elapsed time, with variations such as the split-seconds chronograph for simultaneous timing; the Rolex Daytona, particularly its "Panda" variant, remains an iconic example. The day/date complication indicates both the day of the week and the date of the month; the Rolex Day-Date, introduced in 1956, revolutionized wristwatches by displaying both separately. The moon phase complication visually tracks the lunar cycle, offering an artistic representation of the moon's progression; the Patek Philippe Sky Moon Tourbillon, a marvel of engineering with twelve complications, included this feature and sold for HKD 12,475,000 in 2022. A perpetual calendar advances upon the annual calendar by automatically accounting for leap years, requiring no manual adjustment until the year 2100; an extraordinary Vacheron Constantin 43032 from 1990, featuring a skeletonized design, showcased this functionality. The power reserve indicator informs the wearer of the remaining running time before a watch requires winding, a practical feature found in timepieces such as the F.P. Journe Tourbillon Souverain. A repeater is a highly complex mechanism that chimes the time audibly, with minute repeaters striking distinct tones for hours, quarters, and minutes. The tourbillon, a rotating cage for the escapement, was invented to counteract the effects of gravity on a watch's accuracy, representing a significant achievement in high horology, as seen in the technically complex Richard Mille RM003 AF WG.