In 1884, at the International Longitude Conference held in Washington, D.C., the United States, the world was officially divided into 24 time zones. The longitude line that passed through the Greenwich Observatory was also designated as the primary meridian (0° longitude), Greenwich Mean Time (Greenwich Mean Time). The origin of Time, GMT for short). The prime meridian (the Greenwich Meridian) is the starting point for calculating the geographic longitude, and the time is increased or decreased by 1 hour to 15° to the east or west, respectively.
Rolex GMT Master II
Then in 1930, a genius watchmaker created a watch-sized world time mechanism that could display 24 different time zones at the same time. Due to the time difference, people cannot get the local time accurately, so people have an unprecedented demand for watches that display the time in two time zones.
At that time, Pan American Airlines International requested Rolex to develop a time that allows the wearer to identify the departure and destination time zone at a glance. Thus the first generation of Greenwich watches was born.
There is a 24-hour scale on the Greenwich bezel, and the hands on the dial have a GMT pointer in addition to the hours, minutes and seconds, and are distinguished by red decorations to indicate 24 hours.
The earliest bezel was made of steel, with blue representing the night and red representing the day.
The material used for the outer ring at that time was plastic to reduce reflections, and luminous powder was also filled in the plastic. The luminous powder used radium luminous with radioactive hazards. For safety, Rolex later replaced it with tritium luminous. However, the plastic could not withstand the air pressure and gravity changes in flight and easily cracked, so the bezel was replaced with metal aluminum.
When the GMT Master II was born in 1982, because the main hour hand could be adjusted in units of hours, it was more convenient to change the GMT hands of GMT Master II watches. The mirror surface is replaced by plexiglass with sapphire material, white gold hour markers, and a red and black two-tone aluminum bezel.
- Later, in 1986, Rolex improved the GMT Master movement and replaced it with 904L stainless steel in 1990. The famous Rolex Cerachrom ceramic bezel first appeared on GMT Master II watches in 2005.
Due to technical reasons, the two-tone ceramic bezel was not used until 2013 (black and blue circles)
Firing such a two-color ceramic ring is very difficult because it is necessary to control the “color of the two colors” and the “boundary between colors.” On the blue-black circle, blue is the primary color, and the black part is colored later.
To form this color, it is necessary to immerse the half-side word circle in the compound solution. After adding the solution, the ceramic will be sintered to become strong and form the desired color. During this sintering process, the ceramic will become dense, and the added compound will react with the essential elements of the Cerachrom word circle. Eventually, the color of the half-circle will turn black. The two-color areas of the word circle are in sharp contrast, and the boundary is precise and accurate.,and then the precious metal version of the red and blue circles was also declared breached.
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