Bezel: A ring of metal that surrounds the dial. Sometimes this is simply a polished piece of the case, such as on a dress watch, and sometimes topped with an insert that’s inscribed with numbers and is used to measure elapsed time, speed, second time zones, etc. Some of these move unidirectionally, and some move in both directions depending upon the function of the bezel.
Bracelet: The piece that attaches the watch “head” to your wrist. This could be a metal bracelet, or a strap made of rubber, nylon, leather, or another material. (Leather straps shouldn’t be used underwater, however.) Certain watch bracelets, such as the Rolex Oyster used on the contemporary Submariner, have special claps that allow them to expand and fit over a wetsuit.
Crown: The round piece protruding from a watch case — often, though not always, on the right — that is used to set the time, date, and possibly other functions. On certain automatic watches, it can also be used to manually wind the movement. And on dive watches, it generally screws down to prevent water incursion into the watch case.
Crystal: The glass that covers the dial, this piece was made of acrylic for many decades. On certain less expensive watches, it’s made of mineral crystal, but these days, most divers feature a sapphire crystal. (Acrylic scratches easily but is easy to buff out; sapphire is basically scratch-proof. Mineral is somewhere in between.)
Dial: The part of the watch that tells the time, containing the markers and the hands. Also called a watch “face” — though “dial” is the word that’s used within the industry.
Lume: A term that encompasses the different types of luminescent material used to make a watch dial glow at night or in murky conditions. In the 1940s and 1950s, this material was still radium — a wildly radioactive compound. It was replaced with tritium in the 1960s, which was much less dangerous to handle. Eventually, in the late 1990s and early 2000s, non-radioactive LumiNova was used. These days, the compound used most frequently is Super-LumiNova, though certain companies have proprietary compounds, and a few even used tritium contained in small glass “microtubes.”
Markers: Also called indices, these are the bits on the dial that indicate numbers 1-12. Sometimes, such as on a Rolex Submariner, they’re round “plots,” while on other watches, they’re Arabic numerals, Roman numerals, or a mix of all of the above. On dive, field, and pilot’s watches, they’re almost always coated in luminous material. Markers can be painted or applied physically to the dial.These 10 options, from the Air-King to the Cellini Danaos, are the easiest way into the Crown
Movement: The engine that makes the watch run and tell time. This could be mechanical, requiring hand-winding each day or every several days — though dive watches are almost never hand-wound; automatic, in which a small oscillating weight winds the watch while it’s being worn; or quartz, meaning a battery powers a tiny quartz crystal that regulates the timekeeping. (There are certain hybrid systems that meld these technologies together, but these three are most common.)
Water Resistance: Most
modern dive watches adhere to the ISO 6425 standard and feature at least 100m of water resistance. (Many feature 200m or even 300m of water resistance.) In practice, 100m is plenty, as most recreational divers don’t venture past 40m in depth. Interestingly, many watch companies used to use the term “waterproof,” but this is no longer the case, and no timepiece can fully be considered 100% resistant to water incursion. (At
some depth, it will fail.)