G
GMT watch -On GMT watches, wearers can display the time of a second adjustable time zone, in addition to the local time. In order to be able to read the second time without problems, these watches usually feature a 24-hour display so that a distinction can be made between day and night.
Grande complication -A grande complication is a watch in which several large complications are built into one watch. Many watch manufacturers also label the flagships of their collections with the title "Grand Complication".
Gold - Gold may be used to make watch cases, bezels, bracelets and the most precious parts of the movement. However, strictly speaking, the term 'real gold watch' refers to the use of solid gold in, at least, the watch's case. This Rolex Cosmograph Daytona has a case and clasp made of 18ct gold.
Girard-Perregaux - a luxury Swiss watch manufacturer, with its origins dating back to 1791. They are very prestigious and up there with other brands like Audemars Piguet and Patek Phillipe.
Greubel Forsey - a high end watch designer who handmake a very limited number of watches a year. Their watches are some of the most complicated detailed watches out there - and the casebacks are as detailed as the front..
H
Helium valve - This valve is an important component of diving watches. When the watch is submerged or submerged in water, high pressure builds up inside the watch, which would damage the watch if it could not escape through this valve.
Hulk - This is the nickname for the Rolex Submariner (Ref. 116610LV) with a green dial and green cerachrom bezel.
Horology - The art and/or science of measuring time.