On April 21, 1955 Rolex registered the trademark GMT-Master. GMT stands for Greenwich Mean Time of the zero meridian in relation to which the time in every part of the world is calculated.  The watch was born by demand of the airline Pan Am, which needed a watch able to indicate two time zones.

A timepiece to be put in allocation for the pilot, the first official one and the navigator of any aircraft in the fleet to prevent the ones aboard from suffering from jet-lag, not knowing simultaneously the local time at the destination and origin. Thanks to the team led by Pan Am Captain Fred Libby and Rene P. Jeanneret, head of Public Relations of Rolex the 6542 was born - the first GMT-Master - a modified version of a Turnograph 1030 caliber with the addition of a fourth hand mark indicating 24 hours.

The peculiarity of this GMT-Master is the bakelite ring - later replaced with a more durable aluminium insert - in red / blue (red for daytime hours and blue for nighttime) for the steel version and brown for that 18 ct. gold version. The second time zone is read via a lancet with a triangular tip that completes one revolution in 24 hours. This first "GMT" movement was named at first 1036, then 1065 and 1066, and the production started in 1956. The case had a diameter of "only" 38mm. The date was positioned at 3 o'clock and shown in two colors (red and black numbers, alternating).

In 1958, given the growing demand also by Pan Am executives, Juan Trippe, president of the company, did make a hundred copies with a white dial, the last ones produced with the reference 6542. In 1959 the reference 6542 is in fact replaced by 1675: the only sports model was presented directly with the Jubilé bracelet instead of the usual Oyster bracelet. Among the innovations introduced with the new GMT-Master are the parapets for protecting the winding crown, a more obvious knurled bezel, the loops in a sharper profile and the new 1565 movement.
In 1964 the new caliber 1575 GMT was introduced - in 1971 a version with downtime followed - the charging parapets became more rounded and the knurled bezel less marked. Also the dial is open and beneath 6 hours the inscription SWISS became SWISS T <25.

In 1967 the new graphics of the dial showed white text on dull black background and a 24h sphere marked by a larger triangle for more readability. The red / blue bezel is complemented by a black one. In 1981 there was the last major change, the adoption of the 3075 caliber with a quick click of date with ref. 16750 steel (16753 steel-gold, 16758 gold), matte dial with large tritium indices so-called "buckshot" until 1986 when a new shiny dial with white gold rings around the tritium indices called "shorts" was introduced.

In 1983, the GMT-Master evolved into the first version of the GMT-Master II ref. 16760, called "fat lady" for its thicker case and oversized shoulders. The GMT-Master II is equipped with the caliber 3085, which introduces the independent regulation of the 12-hour hand but loses the rapid date. It was only available in a steel version with red-black bezel and featured a mirrored dial with the inscription "GMT-MASTER II" with tritium indices with a white gold ring. It also featured a new sapphire crystal, which was flat compared to the traditional curved plexi glass.
In 1988, the 16750 and 16760 were replaced by the two new references 16700 and 16710. The ref. 16700 available exclusively in steel with sapphire crystal repeats the same functionality of the 16750, but with a calibre 3175 movement which was produced until 2000.

The ref. 16710 with calibre 3185 movement sacrificed the Quick Shutter date in favor of the ability to adjust the hands of 12 and 24 hours independently, thus obtaining the theoretical possibility of indicating three different time zones. It was also available in steel-gold version ref. 16713 and ref. 16718 gold.

Some minor changes were made until 2005 when ref.16570 with calibre 3186 movement was released, that had the same functions of the previous calibre 3185 although actually derived from 3130 used on the new Submariner ref. 14060M. The main difference lies in the time zone setting on the 12-hour hand, which now takes place without any play, and is very precise and smooth, thanks to the movement of the device from the movement to the gear train of the center hands.

Another new feature of the movement is the Triplock crown and the new spiral "Parachrom Bleu" made of an alloy of transition metals such as Niobium, Hafnium and other materials. The indices and the minute and hour hand were enlarged. The bidirectional ring is made of ceramic with a new font for the numbering of the 24 hours. The new case has thicker loops. The Oyster bracelet has the central shiny vest and Deployant closure. Then the "RRR" ring (Rolex Repeater Ring) was introduced, that contains the word "ROLEX" repeated over the entire inner circumference and at 6 hours the serial number is engraved.

Until 2013 the new GMT-Master was produced only with ceramic bezel with black monochrome background, and numbers obtained by milling and subsequent coating with a thin metal layer to get the gold or silver effect. At BaselWorld 2013 a variant with two-tone bezel ceramic black-blue ref. 116710BLNR was presented said Batman. With a case in 904L stainless steel and lacquered black dial. At BaselWorld 2014 instead the new ref.116719BLRO white gold version was presented, which incorporates the traditional red and blue two-tone ring "Pepsi" but in the new version made of Cerachrom, obtained through a patented process that allows you to get ceramic in two colors. The numbering and indexes are made by etching and subsequent PVD platinum.

In addition to these two references currently in production, the Oyster Perpetual GMT-Master II collection includes the ref. 116710LN with black dial, 40 mm Oyster case and bracelet in steel, the ref. 116713LN with black dial, 40 mm Oyster case and bracelet in steel and gold and the ref. 116718LN with green or black dial, 40 mm Oyster case and bracelet in 18 ct. yellow gold.

Bedetti, official Rolex dealer, awaits you in their store in Piazza San Silvestro to show you the entire Oyster Perpetual GMT-Master II collection.