Rolex GMT-Master vs Rolex GMT-Master II - What's the Difference?

What’s the Difference? The Rolex GMT-Master Vs. The Rolex GMT-Master II

There aren’t many, but there are a small handful of designs that hit exactly the right visual note straight from the get go, and have gone through sometimes decades of production needing nothing doing to them bar the occasional upgrade in their technology.

Porsche managed it to some extent with the 911. At the other end of the car spectrum, the Land Rover Defender also fits the bill.

In the world of luxury watches, Rolex can lay claim to more of these ageless designs than any other manufacturer.

Models such as the Submariner, the Datejust or the Day-Date have evolved so deftly through the generations that the parallels between their earliest and most up-to-date references are instantly recognizable.

What’s in a Name?

Another watch that embodies this perennial styling philosophy perhaps as well as any is the GMT-Master.

Hold an original piece from 1954 up next to one of today’s ultra sophisticated, Cerachrom-infused works of art and it is very apparent there is nothing but a gentle evolution at play.

In fact, the biggest difference between the two, from the outside at least, is in the name. So how, and why, did we get from the GMT-Master to the GMT-Master II?

Born of Necessity

The origins of the first of the GMT-Masters is well known. In the 1950s, with the introduction of the Boeing 707, long-range, transatlantic flights started to become more commonplace.

But while journey times were being slashed and the world was getting smaller, a new problem was emerging—jetlag. Suddenly being dropped into a time zone several hours ahead or behind what your internal body clock was expecting was playing havoc with traveler’s circadian rhythms. Inconvenient for businessmen and vacationers; potentially disastrous for pilots.

It was a big enough area of concern for one airline, Pan American, to commission research into the phenomenon, the results of which found that keeping their air crew on ‘home’ time but also aware of the hour at their eventual destination went some way in combatting the psychological effects.

The obvious solution was a watch that could display two time zones simultaneously, so the task of creating one was given to Rolex, working in conjunction with a Pan Am team led by legendary navigator Captain Frederick Libby. A decorated WWII veteran and one of the original ‘Skygods’ (the name given to those who had flown for the airline before the war), Libby and Rolex’s head of public relations Rene P. Jeanneret, developed on the concept of an already existing watch in the Rolex catalog.

The ref. 6202 Turn-O-Graph was Rolex’s first serially produced watch to use the idea of a rotating bezel, and it was a model that was to become standard issue for a different breed of aviator when it was named the official timepiece of the Thunderbirds, the USAF Air Demonstration Squadron.

Eminently useful, the graduated surround also became a trademark element of the Submariner and, strangely, found its way on to the earliest examples of the Milgauss.

For the GMT-Master, it was engraved with a 24-hour scale and the watch itself was given an extra hour hand that revolved once a day. Fitted with the same Cal. 1030 movement as the Turn-O-Graph, but with an additional driving wheel and calendar indicator, making it the Cal. 1036, the bezel could now be set so that the new hour hand pointed to a second time zone. To add a further element of convenience, the upper half of the Bakelite insert was colored blue and the lower half red, to give an immediate representation of night and day. It was the color scheme that soon earned the watch the nickname the Pepsi.

The First Step

Like pretty much everything that Rolex touched in the 1950s, the GMT-Master turned to gold. It was an instant success, and quickly grew to be first choice not just for airline pilots and international travelers, but also for the military and even those who went further afield. A number of NASA’s finest, including Jack “Houston, we have a problem” Swigert, were loyal wearers.

The first reference, the ref. 6542, was not without its problems however. The synthetic plastic bezel proved to be too fragile in the heat and would crack, and Rolex had chosen to fill the etched numerals with luminescent Radium, which was soon found to be highly radioactive. In 1956 they were forced to recall all 605 examples that had been sold in the US and replace the insert with an aluminum substitute.

Enduring Success

Only in production for five years, the ref. 6542 was superseded in 1959 by the reference that first springs to collectors’ minds when they hear the words ‘vintage GMT-Master’, the ref. 1675.

Bearing a much closer likeness to the watch as we know it today, thanks to the addition of crown guards, the 1675 was also fitted with one of the first of Rolex’s beloved 1500 series of calibers, the Cal. 1565. Now with COSC endorsement, it gave the watch the right to display the ‘Superlative Chronometer Officially certified’ text on its dial.

It was the model that put the GMT on the map and stayed in production for an incredible 21 years, with the additional release of all yellow gold and Rolesor versions seeing it graduate from tool-like travel companion to full-on luxury adornment.

While it went through a host of minute variations, such as the pointed crown guards giving way to more rounded versions and a number of differences on the dial layout, it remained virtually the same watch until it was discontinued in 1980, with a late change in movement to the Cal. 1575 being the most important upgrade. Although the new caliber brought an increased frequency, up to 19,800vph from the former 18,000vph, along with a hacking function, it still didn’t have the one vital feature of a true GMT mechanism—the ability to separate the two hour hands.

Here’s Where it Gets Confusing!

Ok, so far so good. We have a fantastically popular and aesthetically distinctive globetrotter’s watch, but it has the sole disadvantage of its 12 and 24-hour hands remaining linked, meaning wearers are unable to set the GMT hand independently.

It was a problem carried over onto the ref. 1675’s successor, the ref. 16750, a transitional model produced between 1981 and 1988, even though its updated movement, the Cal. 3075, added the convenience of a Quickset date function.

However, shortly into that piece’s run, the first of the GMT-Master IIs emerged. Still very clearly one of the family, the ref. 16760 debuted a previously unknown color scheme of red and black on its bezel, receiving the immediate moniker the ‘Coke’, as well as a case with a touch of added voluptuousness, landing it with the less flattering ‘Fat Lady’. Or, alternatively, the ‘Sophia Loren’. (I’m almost sure that’s all the nicknames.)

The ref. 16760 needed its more generous curves to house its Cal. 3085 movement, the next generation of the 3000 series that finally uncoupled the pair of hour hands. Now, setting a second time zone could be done instantaneously via the winding crown, with the 12-hour hand able to jump forwards or backwards without affecting the others.

Although the only recently added Quickset date function had to be sacrificed to make way for the new feature, it meant it was even possible to keep track of a third time zone by reading it off the bezel.

Side by Side

While the intention was obviously for the GMT-Master II to take over completely, the popularity of the original series was still so great, helped on by its lower price point, that the two continued to run concurrently for over a decade.

Both ranges went through another revision in 1988. The GMT-Master brought out the ref. 16700, the model that would take it up to its eventual and well-earned retirement 11 years later. Again with a new engine, it retained the non-independent hour hands but reinstated the Quickset date feature, as well as introducing a scratch resistant sapphire crystal and indexes surrounded in white gold.

For the Fat Lady, she was granted a return to more slender bodywork by the replacement ref. 16710, powered by the identically functioning but more space efficient Cal. 3185.


Minor visual refinements aside, the GMT-Master siblings are two watches separated by a single, yet critical, function.

Always striving to offer wearers the best possible experience, the capacity to set the 24-hour hand in isolation brought the range the sort of added benefit on which Rolex had built its reputation.

Never a brand to issue an update for its own sake, changes made to any model in their lineup have to serve a definite purpose, and the GMT-Master II seems like a piece that was always waiting to happen, lingering in the background until the necessary technology had been perfected.

Today, it remains one of Rolex’s core offerings; a subject of their relentless progress with, since 2005, that emblematic bezel forged from nigh-on unbreakable ceramic and with a movement crammed full of cutting edge components.

It is a name that has been with us for over 60 years, with no reason to doubt it will be here for 60 more. Although the Sky-Dweller may be the official flagship dual time zone watch in the Rolex stable, for most, the GMT will always be the master.

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