Before taking a closer look at some watches with a GMT complication and dual time zone, let’s first discuss the actual meaning of GMT and its function. GMT is short for ‘Greenwich Mean Time,’ which is the mean solar time at the Royal Observatory in Greenwich, London. Greenwich is notable for its maritime history and for giving its name to the Greenwich meridian, which is also the zero meridian.
Time zones are then displayed as GMT plus or minus ‘x’ amount of hours, depending on the location and distance from Greenwich. The GMT time zone is based on the rotation of the Earth. UTC (Coordinated Universal Time) later became the official time standard, as it is more precise, especially after leap seconds were adopted.
The first Rolex GMT-Master dates back to the 1950s and is said to have been designed in collaboration with Pan-American Airlines for their crew on long-distance flights. In addition to the regular hour and minute hand showing the time, there is an extra hand showing the time in a second time zone. Printed on the rotating bezel is a 24-hour timescale, which allows the GMT hand to show the time as it revolves once every 24 hours. Many GMT bezels feature distinct differences in colour; the colours signify whether it is day or night. Through the years, there have been many variations of the Rolex GMT-Master.
Consistent design is clearly recognisable from the very first Rolex GMT-Master with reference 6542, to the later model 16710 with its blue/red bezel. In the early years the bezel was made of bakelite. This version is also known as the ‘Pussy Galore,’ named after a character in a James Bond movie who wore this exact model on her wrist. Until 2007, it was produced with an aluminum insert that has now been replaced by ceramic. At first, it only came in black, but now it’s available in black/blue and red/blue for the white gold GMT.
Patek Philippe Nautilus Travel Time Chronograph 5990/1A-001
Only launched a few years ago, the Patek Philippe Nautilus 5990/1A-001 is self-winding chronograph with a dual time zone that keeps the original 70s Nautilus design clearly visible. The standard time zone, displayed as local, is set as always using the crown. Underneath the ‘Local’ text on the dial, there is a small window showing whether it is day or night. On the left side of the 40.5-mm stainless steel case, two buttons have been created to set the second time zone, displayed as “Home” on the dial. This time zone also comes with a day/night indication.
The second time zone is read via an extra skeletonised central hour hand. It is easily adjusted one hour forward or back at the push of the respective button. As mentioned, the Patek Philippe also has a chronograph function with a 60-minute counter at 6 o’clock. Finally, there is a date display on a sub-dial at 12 o’clock which can be corrected using a small hidden pusher on the top right side of the case.
Jaeger-LeCoultre Grande Reverso Duoface
Another interesting watch with a dual time zone is the Jaeger-LeCoultre Grande Reverso Duoface. With an original design dating back to 1931, the Reverso has the longest history in this article. Yet unlike the watches above, the Reverso doesn’t just have an extra hand for a second time zone, but rather two different faces. Each face displays a different time zone. By flipping the case, you can see the local or home time. On one side you have the regular time with a small seconds display at 6 o’clock.
When you flip the case to the other side, there is a second time display with a day/night indicator. The Reverso Duoface is available in various case material and strap combinations according to your taste and liking. As the Duoface comes with two different-looking dials, this watch also makes a great choice when you want to change looks from time to time.