How Watches Work
In addition to their exterior beauty, watches are also an incredible feat of engineering and craftsmanship. Many complicated parts must all work in tandem in order to not only tell time, but perform the myriad other functions that many of today’s watches perform. This section contains an overview of the major parts of a watch, as well as an explanation of how watches operate.
Watches contain many parts that work together to tell time, as well as perform other useful functions. These could include a chronograph, altimeter, alarm, day/date calendar, phases of the moon, slide-rule, etc. Here are descriptions of the major internal and external parts and their functions. For more detailed explanations, you can also visit our Watch Glossary.
External Watch Parts
CrystalThe cover over the watch face is called the crystal. There are three types of crystals commonly found in watches: Acrylic crystal is an inexpensive plastic that allows shallow scratches to be buffed out. Mineral crystal is composed of several elements that are heat-treated to create an unusual hardness that aids in resisting scratches. Sapphire crystal is the most expensive and durable, approximately three times harder than mineral crystals and 20 times harder than acrylic crystals. A non-reflective coating on some sport styles prevents glare. HandsA watch's hands are the pointing device anchored at the center and circling around the dial indicating hours, minutes, seconds and any other special features of the watch. There are many different types of hands:
Alpha: A hand that is slightly tapered
Baton: A narrow hand sometimes referred to as a ‘stick hand’
Dauphine: A wide, tapered hand with a facet at the center running the length of the hand
Skeleton: Cutout hands showing only the frame
Luminous: Hand made of skeleton form with the opening filled with a luminous material
The surface ring on a watch that surrounds and holds the crystal in place is called the bezel. A rotating ratchet bezel moves in some sport watches as part of the timing device. If rotating bezels are bi-directional (able to move clockwise or counter clockwise), they can assist in calculations for elapsed times.
The nodule extending from the watchcase that is used to set the time, date, etc. is called the crown. Most pull out to set the time. Many water-resistant watches have crowns that screw down for a better water-tight seal.
The watch face that contains the numerals, indices or surface design is called the dial. While these parts are usually applied, some may be printed on. Sub-dials are smaller dials set into the main face of the watch. These can be used for added functions, such as elapsed times and dates.
Case (or Watchcase)
The watchcase is the metal housing that contains the internal parts of a watch. Stainless steel is the most typical metal used, but titanium, gold, silver and platinum are also used. Less expensive watches are usually made of brass that has been plated with gold or silver.
A bracelet is the flexible metal band consisting of assembled links, usually in the same style as the watch case. Detachable links are used to change the length of the bracelet. Bracelets can be made of stainless steel, sterling silver, gold, or a combination.
A strap is simply a watchband made of leather, plastic or fabric.