Through the clarity of the sapphire dial revealing an open-hearted mechanism, this new Chronomaster El Primero flaunts its palpitating pace for all to see. Artfully staged within an 45 mm-steel case, its high-frequency skeletonised mechanism reveals its unique style in a spirit of complete transparency.

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With its powerful build framing a clear view of its legendary mechanism, the new Chronomaster El Primero Grande Date Full Open unveils the heart of performance and precision in the inimitable Zenith style. This self-winding skeleton-worked chronograph, equipped with a column wheel and a silicon escapement, is highlighted by a dial carved in sapphire. This modern architecture with its striking red accents is designed to be admired from both sides.

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The crystal-clear sapphire dial features two transparent blue- and grey-tinted counters – the aesthetic signature of the original 1969 model – and shows the moon & sunphases on twin discs at 6 o’clock. A silver-toned inner bezel ring surrounded by a blue ring, a black and white minute scale, along with luminescent facetted hands and hour-markers, all contribute to ensuring optimal legibility, yet without obscuring the view of the fascinating inner workings.

The large date at 2 o’clock – shown by two concentric discs with cut-out numerals – is read off against a bright red background in an engraved aperture, while the slim red-tipped central sweep-seconds hand adorned with the emblematic Zenith star sweeps over this perfectly clear display.

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Topped by a domed crystal and fitted with a sapphire crystal case-back, the 45 mm-diameter case – water-resistant to 100 metres – reveals on both sides the outlines of an in-house ‘engine’ with legendary origins. The El Primero integrated automatic column-wheel chronograph beats at the fiery pace of 5 Hz, thereby ensuring and displaying 1/10 second precision.

These sterling attributes are inherited from its illustrious predecessor, the world’s most accurate series-made chronograph developed by Zenith and presented in 1969.

Spotlight on the high-frequency oscillations of El Primero Calibre 4047B equipped with a silicon lever and escape-wheel, this 332-part movement drives central hours and minutes hands, along with small seconds, chronograph, large date, moon & sunphase functions, while maintaining an over 50-hour power reserve. The celestial kinetic ballet is shown on two superimposed discs, with the moon disc rotating every 59 days (two lunar cycles) and the day/night disc making one full turn in 24 hours.

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The stature of the Chronomaster El Primero Grande Date Full Open, complete with its fluted crown and double round pushers, is further enhanced by a steel bracelet or a black leather rubber-lined strap. Another version is available with a two-tone exterior (stainless steel case with a pink gold bezel), teamed with a chestnut leather strap.