There is only so much space on a watch. Even on the largest examples, it takes some virtuoso microengineering to make room for every function while still keeping the piece wearable. As such there is very little left extraneous, with every separate constituent typically put to some kind of use.

One element that has graduated beyond the merely decorative is the bezel. With the arrival of the tool watch in the 1950s, the bezel was found to be the ideal component to entrust with any number of tasks. Its utility was further enhanced when the first rotatable surround was developed.

What’s more, by just employing a variety of different markings, they could be used to help in a wide range of calculations without actually having to alter how the watch itself worked. It has since become a deceptively simple yet highly effective apparatus, with a myriad uses across many fields and occupations.

Below we look at some of the most popular styles of bezel and just how they are used.

The Count-Up Bezel

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The Count-Up Bezel

One of the simplest uses for a bezel arrived with the introduction of the dive watch. Rotatable surrounds had actually been in existence since the 1930s when Rolex fitted one to their ref. 3346 Zerographe.However, contrary to popular belief, it was not the brand’s iconic Submariner that was the first to use a turning bezel for the burgeoning sport of Scuba diving. That distinction goes to the Blancpain Fifty Fathoms, released a year earlier in 1953.

The bezel, engraved with a 60-minute scale, acts as a count up. At the beginning of a dive, the wearer simply aligns the minute hand with the zero marker, usually a triangle, and then they are able to quickly read off their time underwater as the hand moves round.

Interestingly, the modern day requirements for a dive watch, as laid down by ISO 6425, specifies the bezel must only turn in one direction, known as unidirectional. It is a safety feature meaning that if the surround is knocked at all during the dive, it will only move anti-clockwise and so overestimate the dive time rather than underestimate, leading to a diver surfacing sooner.

But the patent for the unidirectional bezel was held by Blancpain until 1983; every other watch up until that time (including the Submariner) had bezels which turned in either direction. Therefore, any non-Blancpain model made before then is not technically a dive watch.

The Count-Down Bezel

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The Countdown Bezel

The logical companion to the dive bezel from above, the countdown bezel works in the same way but opposite. Instead of a scale counting up from 0-60, the markings around the outside count down from 60 to zero.

In truth, as the bezel is doing the same job as the minute hand alone—calculating time as it passes—it has fewer applications. However, by aligning the marker with the minute hand it gives the wearer the ability to keep track of the time remaining for any specific job. Still a useful tool, but rarer in the real world than the count-up bezel.

The GMT Bezel

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The GMT Bezel

If the countdown bezel has limited utility, then the GMT bezel may well be just about the most useful type there is.

Another example that came about in the 1950s at the dawning of the jet age, they were developed out of necessity as the first intercontinental air travel routes introduced an all new phenomenon; jetlag. Crossing several time zones in rapid succession led to the debilitating effect on both passengers and, more dangerously, pilots.

Research by Pan Am Airways, among others, concluded that being able to keep an eye on both the time at home and at the eventual destination simultaneously could help offset the worst of the condition.

The airline teamed up with Rolex to develop a watch that could achieve the feat, leading to the GMT-Master.

The thinking behind GMT watches is brilliantly simple. A second hour hand is geared to run at half the speed of the main hand, and points to a 24-hour scale engraved on the bezel.

Usually, the wearer sets the local time on the regular 12-hour dial and uses the extra hand and bezel to indicate home time. The GMT hand is generally given a different shape and color for easy identification.

With most types the watch can be used to track a third time zone as well. By actually rotating the bezel forwards or backwards by the required number of hours (i.e. the number of hours ahead or behind Greenwich Mean Time your third time zone is), it can again be read off with the GMT hand.

However, doing that loses the 24-hour feature, so it is possible to get confused whether you are looking at 10am or 10pm for example. As a remedy, many GMT watches have a two-tone bezel. Perhaps the most famous example is the Rolex GMT-Master’s red and blue Pepsi color scheme; the red indicating daytime, the blue for the night.

The Tachymeter Bezel

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The Tachymeter Bezel

After diving and GMT bezels, the tachymeter bezel is possibly the most popular type.

Unlike those other two, tachymeter bezels are non-rotatable (called fixed), and are used in conjunction with a chronograph—a mechanical stopwatch.

Featuring ascending markings going counterclockwise around the outside, the function of a tachymeter is to allow the wearer to determine an unknown speed or distance, and combine it with elapsed time.

As such, they were originally found on motor racing watches in the days before electronic timing apparatus. But perhaps the best known example is on the Omega Speedmaster, the first watch on the moon.

Using a tachymeter bezel is relatively simple. If you want to know how quickly you cover a mile, for instance, you start the timer as you set off and stop it again once you have reached the distance. It is then merely a case of reading off the number on the bezel that the seconds hand is indicating. So, if it took 40 seconds to go the mile, the logarithmic scale on the surround tags your speed at 90mph, or km/h if that is how the measure is set up.

Likewise, if you want to know how far you have travelled in a set time, you just need to know the speed you are going. If you are driving at 100mph, you set the chronograph off at 0, wait until the hand aligns with the 100 position on the bezel (a little after the seven o’clock) and you know you have travelled one mile, providing your speed remained constant.

In that way, tachymeters can be used to keep track of just about anything, so long as it occurs in that period of between around 10 seconds to one minute.

One such variation is the pulsometer, used by medical professionals. A specially calibrated tachymeter is used to measure the number of a patient’s heartbeats over a given time. They are sometimes found on the same watch as an Asthmometer, which determines respiratory rate in a similar way.

The Slide Rule Bezel

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The Slide Rule Bezel

A slide rule bezel is unusual in that it operates separately from the watch’s hands and is a calculation device in its own right.

A once indispensible tool, particularly for professional pilots, it is most famously found on Breitling’s Navitimer and can be used to make rapid computations by means of its two mathematical scales.

The first is marked on the rotating outer bezel, the second printed on the perimeter of the dial itself. Working together, they can be used to perform basic multiplications and divisions, measure airspeed, calculate fuel consumption, convert miles to kilometers and a host of other vital requirements.

An extremely complex looking instrument, slide rules take some getting used to, but the simplest functions can be picked up quickly. If you just wanted to multiply 16 x 14, for any reason, you would turn the outer bezel until the 16 lines up with the number 10 on the inner scale (10 is used as the base conversion factor, or reference point). It is then just a case of finding the number 14 on that same interior scale and reading off the number underneath, in this example 224.

Divisions can be performed in a similar way, but beyond that it is usually necessary to spend some time learning the various methods.

The Compass Bezel

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The Compass Bezel

Generally speaking, any mechanical watch can be used as a compass. In a pinch, if you hold the watch horizontal and aim the hour hand at the sun, the point between the hand and the 12 o’clock index is south, if you are in the northern hemisphere. If you are in southern hemisphere, you can employ the same method but use the 6 o’clock index rather than the 12.

However, there are watches which have compass points engraved on the bezel which simplify the whole thing.

Using the basic technique from above, you simply rotate the surround until the South mark is halfway between the hour hand and the 12 marker. Then align the hour hand with the sun and you can read off the various cardinal points on the bezel.

It is far from the most accurate system for orientation, and is very much a backup should all others fail, but it is a useful standby. It is recommended to recheck your direction every hour to keep on course.

Summing Up

That’s our rundown of the most common and popular types of bezel. They have become a multifaceted element on a number of watches, and even if there usefulness has been superseded by a swarm of electronics in recent years, they retain an old school analogue charm that is hard to beat.