One of the many reasons why people love the classic Omega Speedmaster Moonwatch is because of how little its overall design has changed throughout the years. No timepiece can remain in continuous production for over half a century without evolving in some capacity; however, Omega still sells a version of the Speedmaster that is (almost) identical to the original design from 1957.
Today, Omega offers their classic, manually wound, Speedmaster Professional Moonwatch in two different configurations. The first is the traditional version that uses a stainless steel caseback and a Hesalite (acrylic/plastic) crystal; the second variation swaps out the solid caseback for a display back, and the Hesalite crystal for a sapphire crystal, earning it the nickname, the “Sapphire Sandwich” among enthusiasts and collectors. Although the movements used inside the two watches are the same from a functionality standpoint, the version inside the “Sapphire Sandwich” (caliber 1863) is more ornately decorated than the variant in the regular version (caliber 1861), as it is constantly on display through the watch’s sapphire caseback.
Omega first started using display casebacks on the Speedmaster around 1980; however, until roughly 1987, they were only fitted to limited edition or numbered pieces, rather than regular production models. For a brief period of time between 1987 and 2003, Omega produced a different, regular production run variation of their classic, Speedmaster Professional Moonwatch, which offered customers the best of both worlds, and was a 50/50 mix between the two versions of the Speedmaster Professional Moonwatch the can be found in the present-day Omega catalog.
The first non-limited edition, Speedmaster Professional to receive a sapphire caseback was the reference 3592.50. From the front, the watch had an identical appearance to the regular Speedmaster Professional, complete with its signature, domed Hesalite crystal. However, flip the watch over, and visible through its sapphire caseback is the gilt-finished, caliber 863 movement. The reference 3592.50 remained in production until roughly 1996, and due to the timing of its production run, nearly all examples originally left the factory with tritium dials and hands.
Around 1996, Omega phased out the reference 3592.50, and replaced it with the near identical reference 3572.50. The primary difference between the two watches was the movement that was fitted to them. The reference 3572.50 received Omega’s caliber 1863 movement, which ditched the golden-color of the caliber 863, and replaced it with rhodium finishing and Geneva stripes. Around 1998, Omega began fitting the reference 3572.50 with dials and hands that used Super-LumiNova to provide them with their luminescence, rather than radioactive tritium like previous models.
By 2003, Omega had discontinued the reference 3572.50, and replaced it with the reference 3573.50, which swapped out the domed acrylic crystal of its predecessor for a box-shaped sapphire crystal – hence its nickname, the “Sapphire Sandwich” Speedmaster Professional. Internally the “Sapphire Sandwich” was identical to the reference 3572.50 and still featured Omega’s caliber 1863 movement visible through its sapphire crystal display caseback. However, the overall look and feel of the dial-side of the watch was significantly altered due to the different shape and material of its crystal.
The reference 3592.50 and the reference 3572.50 are no longer in production; however they now have several different nicknames. During the time that they remained in Omega’s catalog, they were simply known as sapphire-back Speedmaster Professional watches; however many collectors now frequently refer them to as “Hesalite Sandwich” Speedmasters. Additionally, a smaller number of individuals choose to call them “Mullet” Speedmaster Professionals, due to their “business in the front” (NASA-approved Hesalite); “party in the back” (sapphire crystal with decorated movement) construction.
To say that the Speedmaster has remained “unchanged” since its initial introduction more than sixty years ago would be an absolute hyperbole; however the current production model is about as close to the original as one could hope for from a contemporary timepiece. While the standard Speedmaster Professional Moonwatch is faithful to the original, and the “Sapphire Sandwich” is a thoroughly modern take on a classic aesthetic, the “Hesalite Sandwich” Speedmaster references, are the perfect choice for the person who wants the classic Omega Moonwatch, but who also wants to be able to admire the complex inner workings of Omega’s most iconic timepiece.