The following is from "The Best of Time: Rolex Wristwatches: An Unauthorized History" by James M. Dowling and Jeffrey P. Hess, Schiffer Publishing Ltd, ISBN 0-7643-0011-3
After the two-tone Datejust, the Explorer is one of the most easily recognizable of all Rolex models. With its black dial, large luminous triangle marker at 12, and luminous arabic numerals for the other quarters, it is the perfect mixture of a sport and a dress watch. It seems to have been around as long as there have been Rolexes, but that is not exactly true. However, as with most legends, finding the truth is never simple.
Before we get into the history of the Explorer it is perhaps first worth defining the watch itself. The generally accepted definition of an Explorer is that it is any watch with the dial described above. Unfortunately, one often encounters watches with the word "Explorer" proudly printed on their dial, which bear no resemblance to this description. More rarely, one sees an Explorer dial on other Rolex models. In this discussion of the Explorer we are exercising our writers' prerogative and choosing to include all of the above as Explorers.
The generally accepted origin of the Explorer is that it was first designed and made in honor of Edmund Hilary and Tenzing Norgay, who, on May 29, 1953, were the first to reach the summit of Everest and who did so wearing Rolex wristwatches. The only problem with this hypothesis is that it can not possibly be true. The climbers on Everest were, in fact, wearing Explorers. so the watch had to have been introduced before the climb and not after. One of the watches worn on that expedition was auctioned by Sotheby's London on July 19, 1988 as lot 117, (see photograph on page 243). As you can see the watch was a classic early Explorer down to the "Mercedes" hands, except for the absence of the word "Explorer" on the dial. The shape of the watch land the description by Sotheby's as a "Bubble Back" Explorer) leads us to believe the watch is in fact a model 6350. This hypothesis is strengthened by the photograph on page 246 which shows another model 6350 with art almost identical dial. The main difference between the two is that the Sotheby watch lacks "Explorer" but has the word "Precision" above the 6, whereas the other watch has the word "Explorer" but lacks either "Precision" or "Officially Certified Chronometer" above the 6. Instead it has a British military marking in their place, as well as on the case back. In the early 1950s, the period these watches were made, Rolex often stamped the in- side of the case back with the date of manufacture. The military 63,50, marked Explorer, shows the manufacture date as IV 53, meaning the 4th month of 1953. As stated above, Everest was conquered on the May 29, 1953. Using these facts, it seems likely that Explorers were in production prior to the conquest of Everest. It is also worth noting that the name "Explorer" was registered in Geneva on the January 26, 1953, obviously well before the conquest of the world's highest mountain.
While it is true that many of the members of the successful Everest expedition were issued with Rolex watches (see the advertisement on page 243), the embarrassing fact for Rolex was that only one of the two climbers at the top was wearing a Rolex. This watch, worn by Tenzing Norgay, is now in the Rolex Museum in Geneva. Although Rolex was an official supplier to the Everest expedition, so was the English watch company Smith's and Edmund Hilary chose to wear a Smith's watch (see the advertisement below). In the end it was the Rolex publicity machine that triumphed. Interestingly, due to a pact made by Tenzing and Hilary, we will never know which watch was first at the summit; both climbers have always said that it mattered nothing who was first.
The real origins of the Explorer are revealed by its name. It was designed for explorers and so it had a high visibility dial. an extra strong case, and, on request, it could even be lubricated with a special oil which could withstand temperatures of between -20°C and +40° without changes in its viscosity. As such it was used by many expeditions both before and after the successful Everest expedition.
The look of the Explorer is all about the dial, which is a mixture of a number of previously used styles. The large triangle at "12" was first used by the company on the mixed Roman and Arabic dial of the early 1940s. The large arabic numerals for the Quarters and bars for the remainder are seen on many of the very first model cushion Oysters. Despite this somewhat mixed parentage, the dial has taken on an identity of its own and can never be confused with any other.
These first Explorers (6350 models) used the "big bubbleback" 10-1,/2"' A296 movement. Most of the other 63,50 models to have surfaced do not have the classic "Mercedes'' hands. In- stead they have heavily luminized versions of the standard parallel hands of the period. While the sweep seconds hand is very strange, it looks similar to the current hand having a large circular luminous insert. Closer examination reveals that this circular insert is at the tip of the hand, not 4 mm from the tip as now. Most of the early 6350 dials are also unusual in that they are "honeycomb" textured (how the company managed to print on this surface is a mystery) and are signed as "Officially Certified Chronometer." It is difficult to know how successful this model was, for it is not exactly a common piece and seems to have been replaced by the 6150 model within a year or so. Powered by the same movement, the 6150 was distinguishable from the 6350 by being 2mm. larger and was only available as a Precision model. Not all the 6150s were classic Explorers. The one shown in the photograph on page 249 is unusual in that. while it bears the normal reference number, the dial is previously unknown. The 61,50 was made until 1959 when it was replaced by the 6610, which appears identical, but in fact can be identified by its flatter back. a consequence of using the newer 1030 calibre movement". The dial of the 66 ill is signed "Chronometer. " The simplest method of recognizing any of the early Explorers is by looking at the dial. Although they are all steel watches, all of the printing on the dials (the minute track, the Rolex logo and the model name) is in gold.
During these early days of the Explorer, Rolex was unsure of the model's potential. As a result the name was affixed to a number of watches not immediately recognizable as Explorers. Today the name and the look are so intimately entwined it seems ridiculous to apply the name to watches which were so obviously not what we would call Explorers. But it happened, and the results are some of the rarest Explorer models known. There were two distinct variations on the theme and they seem to have been aimed at two distinct markets. The first was the so-called "Air-King" Explorer. This was an Explorer bearing the 5500 model number usually applied to the Air-King, but with an Explorer dial that is marked "Precision" rather than the "Superlative Chronometer Officially Certified" we would expect to see. There has been some doubt that these watches are real, for, if we examine the watch closely, we can see that the dial is smaller than a normal Explorer dial. But the receipt from Rolex, shown on the previous page, lists a 5500 Explorer. With this information we think we can validate these as genuine Rolex pieces. A closer examination of all of these models which have turned up with original paperwork reveals one further interesting fact. All of them were purchased from N.A.A.F.l. (the British equivalent of the PX) in the middle or far east. Whether or not the model was made as a comparatively inexpensive military style watch for officers to purchase with their own money is just one more question waiting to be resolved.
The second variation on the theme are "dress Explorers." These are standard Oyster Perpetuals in steel or gold with white (or more rarely, black) non-Explorer dials featuring gold markers and hands, but signed "Explorer" on the dials. Seen in both date and non-date forms, these watches all seem to have been sold in the North American market. The Explorer Date, shown bears a model number 5700, previously unseen on any other Explorer. The non-date model is a model 5504, which interestingly is more often seen on Explorers with the standard dial. We have even seen a gold capped Explorer with a Tiffany dial with the reference no 5510. The earliest one of these to turn up has been a model 6298, having the manufacture date of ii1 53, and bearing the phrase "Self Winding" more often seen on Tudor watches. It seems that these watches were made in the 1950s or 1960s when Rolex was unsure if the Explorer would succeed or not, and attempted to increase the popularity of the watch by broadening the line. When the mainstream Explorer began to sell it seems that these "piggyback" models were with- drawn. This is one more example of the bizarre fact that it is a company's failures that become the most desirable and valuable items in any collection.
Perhaps the strangest "Explorer" model is not really an Explorer, but a Submariner. It is a model 5513 non-date, non- chronometer watch with a classic "Explorer" style dial. The watch seems only to have been sold in the UK and only for a short period in the 1960s. The catalog shown bears the date 1966 and was a catalog only for the British market. One of these watches has surfaced with a hacking seconds movement (which would date it after 1972), also in the UK.
The introduction of the 6610 model in 1959 gave us the Explorer in its most recognizable form. Only in production for five years, the 6610 differed from the 1016 that replaced it in calibre; the 6610's calibre 1030 was replaced with the more modern calibre 156049. While the cases of the two watches looked almost identical, the new model was now guaranteed waterproof to a pressure of 10atm rather than 5atm of the 6610.
The 1016 Explorer was the longest running of all the models, being in production from 1963 right through to 1989. During this period it did not, however, remain unchanged. The first model (in production from the start to around 1975) used the basic calibre 1560, but, as is the general Rolex policy, there were certain updates and modifications. While there are some watches signed Explorer that do not look like regular Explorers, the 1016 also exists with another name on the dial: "Space Dweller." The model was first introduced into the Japanese market in 1963, just after a visit to Japan by the Mercury astronauts. A trial run of Space Dwellers was made to honor these men, who were (at that time) seen as the ultimate explorers. The watch was not a major seller, either in Japan or elsewhere, and very few of the watches so signed have ever surfaced.
The second version of the 1016 was really the second version of the 1560 calibre (now renamed 1570), because the major recognizable difference is in the movement. The "hack" feature, stops the second hand when the winding crown is pulled out to the hand setting position. By stopping the hand at the "12" position, it is possible to synchronize your time with that of a known source, a radio or telephone time signal for example.
Simultaneously with the movement change, Rolex introduced the new Oyster bracelet. It had links machined from solid steel, instead of the folded sheet steel of earlier bracelets. In this revised form the Explorer continued through to 1989, when, to the astonishment of the Rolex retailers, it was removed from the new catalog. It was only six months before a new very heavily revised Explorer arose from the ashes of the 1016. The new model, bearing the model designation 14270, sported a new case, dial, movement, and glass. It seemed as if the hands and the name were the only things carried over from the 1016 Almost thirteen years after Rolex had first introduced the sapphire crystal, the Explorer was finally fitted with one. Under this new crystal, the dial featured white gold skeleton markers with luminous tritium fillings; these replaced the previous painted dial markers. Under the dial was the very latest fast beat calibre 3000. These modifications brought the Explorer in line with all other Rolex models and because the cosmetics of the new watch were so different, they sent the prices of the older models in the collectors market on an upward spiral. The result is that, at this writing (early 1996), collectors are paying more for the older models than the retail price of the new one.
The other Explorer is the Explorer Il. Introduced in the early 1970s as model 1655, it is essentially a GMT-Master with a fixed bezel. Using the same calibre 1575 movement as a GMT- Master, it also had a fourth hand which rotated once every 24 hours, however on the Explorer II the hour was read from this from a fixed, engraved 24 hour steel bezel. The watch was introduced as being especially useful for the speleologist ( or cave explorer), who, Rolex claimed "soon loses all notion of time: morning, afternoon, day, or night. " For these intrepid souls Rolex developed the watch which would tell them whether the "2" on the dial was 2:00 a.m. or 2 :00 p-m. (14:00 hrs). This may well be true, and perhaps cave dwellers are more susceptible to losing track of time than others. We would suggest, however, that the demand for a watch specifically targeted at speleologists would find a tiny market, and that even its limited popularity was due to its acceptance by others who work in civilian and 24 hour time systems, such as pilots and air traffic controllers. The watch went through two styles. The first, made for only three years, used an orange 24 hour hand, and the following model, made until 1985, used a red one. The 1655 Explorer II and the 1019 Milgauss are the only Rolex models which use hands that are used by no other model.
We used the phrase "limited popularity" above intentionally for this watch always was one that was never very widely distributed. It was not really popular until 1991, five years after it was re-launched with a sapphire glass and the same movement as the GMT-Master II. This allowed the owner of the watch to set the hour hand backwards or forwards in one hour jumps without disturbing the second and minute hands. This facility allowed the owner to change time zones without losing a pre- set accurate time.
The new watches, like the first model Explorer II's had the bezel numbers enameled in black, but the very first of the new model Explorer lls had very unusual red bezel enameling. These early white dial models had the tritium dots and the hands out- lined in white gold, while the following models had them out- lined in black.
The name, Explorer, and its whole history of promotional material have made much of the watch's ability to resist hazards and we are sure that this reflected glory is the reason for the watch's continued popularity. In the end wouldn't we all like to be thought of as "Explorers"?