Longines has had an obsession with high-frequency regulated timing devices for well over a century now. The manufacture created their first 5Hz stopwatch with flyback function, capable of measuring 1/10th of a second, as early as 1914, and then proceeded to outdo themselves with a 50Hz stopwatch in just two years, in 1916. With a balance that clocked in at 360,000 vibrations per hour, the device was capable of measuring time up to 1/100th of a second. As the wristwatch gained in popularity, Longines brought their high frequency know-how to bear in this new form too. To make a point, the manufacture began sending these high frequency wristwatches off for certification to third-party validators and chronometric competitions held by the highly regarded observatories, such as the Observatoire de Neuchâtel, and the Contrôle Officiel Suisse des Chronomètres (COSC). Needless to say, Longines claimed multiple accolades. 

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This acclaim gave Longines the confidence to push boundaries further, eventually challenging even electronic watches. Because high-frequency watches beat faster, they also exhaust their power reserves a lot quicker and the components wear out faster. To circumnavigate this, Longines patented a dry lubrication in 1966, which among many other points of fine tuning, allowed for the calibre 431. This movement was able to guarantee accuracy of a minute a month, or two seconds per day. Such a standard far exceeded the requirements of COSC, the chronometer certification body and thus, Longines boldly named the calibre 431-powered wristwatch, the Ultra-Chron. 

Still in the 1960s, Longines moved to case up calibre 431 into a 200m water-resistant dive watch dubbed the Ultra-Chron Diver. Here is where we pick up the linage of the 2022 reissued Ultra-Chron Diver. The contemporary Ultra-Chron Diver has been rendered in the same cushion-shaped case of a particular 1968 Ultra-Chron Diver, along with its striking red minutes hand. Looking to the unidirectional bezel next, we must acknowledge that Longines has placed a sapphire insert on it with Super-LumiNova so that the dive bezel remains legible in dimmer conditions. 

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For the movement, Longines, in partnership with ETA, has developed the new calibre L836.6, which boasts a frequency of 5Hz. And in the spirit of the Ultra-Chron’s legacy, to show again that Longines’ is not simply blowing its own high-frequency horns, the new Ultra-Chron Diver has been chronometer-certified by TIMELAB, an independent entity that is also in charge of the Poinçon de Genève mark of excellence. TIMELAB subjects the timepiece to a series of tests over 15 days, through which the watch is measured for accuracy at three temperatures: 8°C, 23°C and 38°C. However, what sets TIMELAB apart from its contemporaries is that its certification is based on testing cased-up movements — actual watches. COSC, by way of contrast, confers its certification on base movements. 

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