You will always find there is a bezel on a diving watch, but do you know why and how to use the bezel to calculate?
Divers have to carry an oxygen tank when they dive under the water, and the amount of oxygen is related to the size of the oxygen bottle, so the divers will bring a device to measure the amount of oxygen. That’s why diving watch was created.
The rotating bezel features a diving watch and plays a role in reminding the diving time. The marking scale of the rotating bezel is 15, 30, 45, because the oxygen cylinder of general diving can only adhere to 45 minutes, and some are marked with a 60-minute scale. The first 15 minutes are colored or specially marked, because divers will strictly observe a 15-minute safety stop when ascending to completely release the nitrogen absorbed from the cylinder.
Generally, as long as you rotate the bezel and align 0 with the minute hand during diving, the 0 scale on the bezel is aligned with the minute hand, and then you can know the diving time by checking minute hand moves.
Usually the bezel is designed to be single directional which is to ensure that the calculation time is only accounting for more, not accounting less, so to prevent misuse and prolong the time out of danger. The marks and hands are luminous, so that it can be clearly read when the underwater light is dim, and the size of the hands and marks are intentionally enlarged to make it easier for users to read. The early luminous material was radium (Radiomir), which was discontinued due to excessive radiation. The most commonly used luminous materials are Super-LumiNova and tritium trachea now. Super-LumiNova is a new material that absorbs the gamma particles in the light to store light and can continue to emit light for more than 10 hours, but the intensity of the light will decay after a certain period.