Rolex produced specific models suitable for the extremes of deep-sea diving, caving, mountain climbing, polar exploration, and aviation. Early sports models included the Rolex Submariner (1953) and the Rolex Oyster Perpetual Date Sea Dweller. The latter watch has a helium release valve, co-invented with Swiss watchmaker Doxa, to release helium gas build-up during decompression. The Explorer (1953) and Explorer II (1971) were developed specifically for explorers who would navigate rough terrain, such as the world-famous Mount Everest expeditions. Another iconic model is the Rolex GMT Master (1954), originally developed at the request of Pan Am Airways to provide its crews with a dual time watch that could be used to display GMT (Greenwich Mean Time), which was the international time standard for aviation at that time and was needed for Astronavigation during longer flights. To date, the Rolex is the most sought after luxury watch in the world. They also retain the highest percentage of their original value in the industry. With a steady 2,000 watch production per day, Rolex watches has created and maintained a demand for superior watches that are a status symbol which will stand the test of time. The Rolex Oyster Perpetual Submariner watches came into existence in the early 1950's when scuba diving was just becoming the newest trend. Divers demanded a watch that can go up to 100 meters / 330 feet underwater and Rolex answered this demand and developed the first ever water resistant watch; the Rolex Oyster Perpetual Submariner. This soon became the divers' chronometer of choice. The Submariner and Submariner Date models use Rolex perpetual movements, the 3130 and 3135. These movements are certified Swiss chronometers, a title designated for only the finest of high-precision watches that have passed the Swiss Official Chronometer Testing Institute tests. After the introduction of this iconic, yet highly durable watch, Rolex allowed this design to evolve and had since equipped their new watch designs with numerous patented technical innovations. Divers have henceforth continued to praise the Rolex Oyster Perpetual Submariner both underwater and on dry land.
Although the original Rolex GMT Master model was available only in stainless steel, as it was conceived as a functional work watch, Rolex has been making luxury versions in both mixed steel and gold, and all-gold since the 1950s, and there are even {special|exotic variations that have creative designs that include precious stones. It’s tough to pick a winner here, but for me it really comes down to the dial design and I’m very much in the Explorer II’s camp on this one. I really like the broader hands and the orange stands out brilliantly against the black dial. I find that the green 24-hour hand on the GMT Master II can get lost in certain lighting conditions due to a lack of contrast with the glossy black dial. The GMT II has a slightly glitzier look to it with the glossy bezel and polished centre links, which gives it a nice presence on the wrist and looks great when paired with smarter clothes. But personally I prefer the brushed finish on the case and bracelet of the Explorer II, as it’s a little more on the subtle side.
In the early 1980s the Rolex GMT Master II was released (although production of the original version continued alongside it until the late 1990s). Although the watch looks almost identical it uses a movement that has the additional capability of an independently adjustable quickset hour hand that can be adjusted to local time without stopping the seconds or disturbing the minutes and 24 hour GMT hand. As the watch continues to feature the rotatable bezel it is able to quickly compute any third timezone reference. An updated Rolex GMT Master II was released in 2005. This new model features a number of technical changes, such as Rolex's patented Parachrom hairspring as well as a larger Triplock crown (from the diver's watches). The new model also has several cosmetic changes, such as larger case, hands and hour markers and also a new bezel made using an extremely hard ceramic material that is designed to be more scratch and fade resistant. Also included in the update is a new and more luxurious style of bracelet that has heavier solid links and a machined clasp. The stainless steel version now joins the precious metal versions by having highly polished centre links on its bracelet, which gives the watch a more dressy appearance but can be prone to scratches when used as an everyday watch.