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The Evolution of the Rolex Explorer II 16570

Running for a strong twenty-two years, the Explorer 16570 underwent eight production cycles with much innovation, yet it always remained true to its essence.
By Gabriele Olivari
Aug 20, 2022

The Rolex Explorer II 16570 was created as a professional watch, with specific functions that were designed to that end. The watch is extremely durable, the bezel engraved with numbers, it includes a GMT function, and the dial sports a high-visibility index. These specifications add up to endurance and nocturnal functionality, as the watch was designed not just for explorers, as the name suggests, but for an even more extreme category: speleologists – cave scientists or adventurers.

By nature, this profession can keep scientists “underground” for prolonged periods of time, researching, exploring, and documenting even the deepest caves, and their role is crucial in the preservation of these dark environments. Yet, when spending days or even weeks far underground without seeing sunlight, one can easily become disoriented, and the sense of time can become distorted. This is extremely bothersome for both scientists and adventurers, who need to remain focused and sharp in order to complete their respective tasks. The Explorer ensures ease of use under extreme environments, its characteristic bezel and its adjustable GMT hand ensure that the speleologists remain connected to the outer world’s time rhythm and lets them organize their sleep cycles according to what their bodies are used to. Of course, the highly visible features of the watch are ideal for dark surroundings.

If this seems outdated, be mindful that the Explorer 16570 was first produced in 1989, as the heir to the Explorer 16550, which came after the Explorer 1655. The 16570 went strong for a mighty 22 years, before the 216570 was introduced in 2011 and the 16570 was subsequently discontinued.

The Explorer 16570 was initially produced with a tritium index in two dial colors, black and white, a 78360-steel bracelet and 701/b ends. First production started with a serial “L” through “T,” remaining unmodified between 1989 and 1996, although some 16570s come with a 93150 bracelet which could be requested after 1995 by paying a slight surcharge. One interesting feature of the first production up to the early ‘90s is the famous chicchi di mais, or "corn kernels." A 16570 with this feature has the index on the dial with a color ranging from a light yellow to a dark ocher. The above and below image illustrate this feature with completely different gradations of the indexes. The index color of the above one, which I had the pleasure of having in my collection, is only slightly different and therefore not considered a chicchi di mais by many people, yet it excellently illustrates the concept. The below photo, provided by a dear collector friend, Simone Laterza, has a homogeneous and spectacular change of color, a real chicchi di mais in great condition.

The standard white dial Rolex Explorer 16570 from first production, that doesn’t feature the chicchi di mais, contains an index that is even whiter than the dial, as can be seen in below photo.

Then there is the 1BIS production (below), which is very similar to the previous one, with changes made only to the bracelet and clasp. In fact, when reaching the serial "W," Rolex began proposing the 93150 (the Submariner bracelet) as an alternative to the classic bracelet with box closure. They were likely already thinking about producing the short flip-lock of the 78790 bracelet, which would also be applied to the GMT 16700/16710, and in the meantime, with a slight surcharge, they opted for the Submariner one.

It was with the second production that the Rolex Explorer became a truly professional watch, in my opinion. With the 78369 bracelet from first production, the bracelet could open at any time if adjusted incorrectly, which was a real flaw given the watch’s purpose. But with the second production evolution, the 78790 bracelet with flip-lock clasp took over. It is similar to the 93150 (Submariner bracelet) but with a shorter clasp, and without the extension for the diving suit.

The end-links remain the same and the dial still features tritium indexes.

With the third production Rolex introduced a very important innovation to the 16570 and the brand’s history at large:  the luminova. 16570s from this production can be recognized by the dial inscription located at six o’clock – instead of “swiss – T< 25” it only says “Swiss,” which is why these examples are also called “only Swiss.”

Fourth production of the 1570 was short-lived. It can be considered a transitional production because it featured characteristics of the later modern ones, such as the super-luminova dial, and characteristics of previous productions like the bracelets with ends and the case with holes. Thereafter came fifth production, which was the first of the modern productions. In addition to the super-luminova index dial, it also came with a SEL (solid end links) bracelet (78790A), meaning that its links and end-links are joined together because the last ones are machined from solid.

It was also with this production that Rolex started implementing the hologram guarantee (with a colored rhombus) – visible in below image of the white-dialed Explorer – which I consider Rolex’s most beautiful guarantee.

The "no-hole case" was the important modification of the sixth production. The case no longer included two holes for inserting the bracelet pins, but two small inner pins on the bracelet that allow its extraction.

The 6BIS production was another transitional production, as the only difference was that these watches came with the brand-new warranty card, which put an end to paper guarantees, making way for plasticized cards.

The seventh production introduced the RRR (Rolex Repeater Ring). The rehaut, the ring that is located below the glass around the dial, is engraved with laser technology, making forgeries more difficult. Finally, eighth production, the last, is the one most valued today, alongside the chicchi di mais, as it contained the new 3186 caliber, which was an evolution of the 3185 with several improvements. As mentioned above, The Explorer II finished its cycle in 2011, with many differences from its first production in 1989, yet until its last rendition it maintained its same identity and professional soul, making it a valued model among the Rolex roster.