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In the pantheon of vintage dive watches, few timepieces offer the specific combination of technical prowess and audacious design quite like the Longines Ultra-Chron. While the Submariner and the Seamaster often dominate the conversation, the Ultra-Chron stands apart as a testament to the “high-beat” revolution of the late 1960s. Longines advertised this line as “the most accurate watch in the world” upon its release, a bold claim backed by genuine horological innovation. This isn’t just a dive watch; it is a piece of engineering history that represents the absolute peak of mechanical timekeeping before the Quartz Crisis changed the landscape of the industry forever.
Launched in 1967 to celebrate Longines’ 100th anniversary, the Ultra-Chron line was defined by its movement: the Caliber 431. This was a high-frequency engine running at 36,000 vibrations per hour (5Hz), significantly faster than the standard 18,000 or 21,600 vph of the era. This rapidity allowed for greater stability and accuracy, a feat that only a handful of manufactures—like Zenith and Girard-Perreguez—could achieve reliably. The Reference 7970 took this dressy, high-tech movement and dropped it into a rugged, sporty chassis. The design language is quintessential late-60s transition, moving away from the slender lugs of the past toward the blocky, purposeful cushion cases that would define the 1970s. It was designed for visibility and utility, with the high-beat movement providing a mesmerizingly smooth sweep of the seconds hand that is a joy to watch even today.
This particular example, the Reference 7970-4, is the definitive execution of the sporty Ultra-Chron. It features a robust cushion case that sits with a commanding presence on the wrist, yet remains surprisingly wearable due to its short lug-to-lug distance. The visual centerpiece is undoubtedly the bezel. While many divers of this era used aluminum inserts, this reference utilizes an acrylic insert, (often referred to by collectors as Bakelite) which provides a depth, warmth, and glossy texture that modern materials simply cannot replicate. The stark contrast between the black dial and the vibrant orange minute hand was a practical choice for legibility underwater, but today, it serves as a fantastic stylistic flourish that screams vintage charm. We also love the applied “Ultra-Chron” logo at 6 o’clock, a stylized spark that hints at the electric performance of the movement inside.
This example has been preserved in honest, character-rich condition. The stainless steel case retains its distinct geometry and sharp lines, showing the expected wear of a life well-lived but avoiding the over-polished look that plagues so many cushion cases. The Bakelite bezel is in fantastic condition, retaining its vibrant orange numerals and distinct triangle indicator, free from the cracking often seen in these delicate components. The matte black dial is clean, providing a perfect backdrop for the tritium lume plots which have aged to a warm, creamy custard hue. The hands show a true “wabi-sabi” charm; the signature orange paint on the minute hand exhibits some cracking and loss, a detail that validates the watch’s originality and adds to its rugged “tool watch” credibility. The movement is clean and correct, showcasing the architectural beauty of the Caliber 431.
