In 1926, Hans Wilsdorf unveiled the Oyster, widely regarded as the world’s first waterproof wristwatch. What remained was to keep it running without having to unscrew its crown every morning. In 1931, Emile Borer, technical director of Aegler in Bienne – the maker of Rolex movements – perfected the “Perpetual” rotor: an oscillating weight free to rotate through 360°, winding the mainspring with the movements of the wrist, without buffers or jolts – the principle still followed today by virtually all automatic movements. The first Oyster Perpetuals were marketed from 1933.
Rather than designing an entirely new caliber, Rolex grafted its winding module onto an existing manual-winding movement. The assembly gained in thickness and, to house it without weighing down the silhouette of the case, the screw-down caseback became domed. This rounded back earned the watch its “Bubble Back” nickname in the English-speaking world – and “Ovetto”, the little egg, among Italian collectors. Rolex itself never used these words: on the dial, the watch is simply called Oyster Perpetual.
The movement evolved quickly. In 1935 came the “Super Balance”, with recessed regulating screws; in 1936, the case went from three pieces to two with references 3131 and 3132, and caliber 630 brought the seconds to the centre, where caliber 620 had relegated them to 6 o’clock. This caliber 630 – 17 jewels, 18,000 vibrations per hour, winding in one direction of rotation only – was adjusted and then certified as a chronometer by an official testing bureau, as attested by the two lines “Officially Certified Chronometer” that sign the dials. It powered the 32 mm Bubble Backs until the end of the 1940s.
Reference 5050, in steel, belongs precisely to these last 32 mm Bubble Backs, produced in the second half of the 1940s: tonneau case with smooth polished bezel, domed caseback with fluted edge, screw-down crown signed “Rolex Oyster” around the Swiss cross. After it, the size grew to 34 mm with the “large” Bubble Backs of 1950-1954, then caliber 1030, thinner and with bidirectional winding, made the domed back unnecessary: by the mid-1950s, the Oyster Perpetual had regained a flat back, and the Bubble Back passed into history. A detail specific to Rolex watches of the period: reference 5050 is engraved between the lugs, while the screw-down caseback, a part the 5050 shares with its predecessor the 2940, bears the latter’s number on the inside.
Our example, whose serial number 661xxx dates its production to 1948, owes its character first and foremost to its dial. Originally ivory in colour, it has developed over the decades a “crème brûlée” patina: a finely speckled caramel background of rare evenness, against which the twelve radium-filled Arabic numerals stand out. The inscriptions – the crown, “Rolex Oyster Perpetual”, the two lines “Officially Certified Chronometer”, the “Swiss Made” at 6 o’clock – and the railway minute track, numbered every five minutes, have remained perfectly legible. This dial is original and has never been restored, and therein, in our view, lies its whole appeal: Bubble Back dials are often seen badly damaged or, worse, reprinted. The blued steel pencil hands, typical of the period, complete the ensemble perfectly. The centre seconds hand, also in blued steel, is fine and elegant.
The 32 mm steel case is in fine overall condition: the smooth bezel and polished flanks have retained their curves, the lugs their shape, and the fluted domed caseback shows only a few superficial scratches; the engravings inside the caseback are crisp and deep; and the reference and serial numbers, engraved between the lugs, are perfectly preserved. The “Rolex Oyster” screw-down crown with Swiss cross is original, and highly sought-after today. Caliber 630, whose gilt rotor bears the inscription “Rolex Perpetual”, has been fully overhauled by one of our experienced watchmakers and runs very well.
We present this watch on a new cognac alligator leather strap hand-stitched by our artisan, whose shade echoes the patina of the dial, fastened with a Rolex steel pin buckle. It comes with our Steel Warranty Card.
The Bubble Back is the first automatic Rolex – the ancestor of all the Oyster Perpetual, Datejust and Submariner models that would follow – and reference 5050 is one of its last expressions in the historic 32 mm size. This one, with its original “crème brûlée” dial almost never encountered so even, is in our view a piece of history to be worn: discreet beneath a shirt cuff, equally suited to both men’s and women’s wrists, for everyday wear as well as for the most elegant occasions.
