Jaeger-LeCoultre Geophysic watches

The Jaeger-LeCoultre Geophysic began in 1958 as a precise, sturdy chronometer for the scientists and explorers who joined expeditions during the International Geophysical Year. The original measured 35 mm, resisted magnetism and ran on the 478BWSbr, the movement Jaeger-LeCoultre also used in its Royal Air Force pilots' watches. Its luminous dots were tritium, painted on the underside of the crystal.

In 2014 the brand remade it as the Geophysic 1958, enlarged to 38.5 mm and water resistant to 100 m. Inside is the automatic calibre 898/1 with a 43-hour power reserve, wrapped in soft iron against magnetism. Steel (8008520) came in 800 pieces and pink gold (8002520) in 300, both with a cross-hair dial; the platinum 800652J, a boutique edition of 58, has a cleaner dial without the cross. All three have faux-patina lume on the hands.

A year later the Geophysic became a collection of its own, with two models in steel or pink gold. The True Second (39.6 mm) runs on the automatic calibre 770, the Universal Time (just under 42 mm, 11.84 mm thick) on the calibre 772. Both have a 40-hour power reserve, the brand's Gyrolab balance, shaped like two arcs rather than a full wheel, and a dead-beat seconds hand that advances one full second at a time. The steel True Second 8018480 with a blue dial is limited to 100 pieces.

The Universal Time keeps a fixed blue planisphere map at the centre of the dial, with a 24-hour ring and 24 cities around the edge. The cities are set with the crown, independently of the time, so adjusting them never disturbs timekeeping. It comes on a strap or on a steel bracelet (8108120). The Geophysic Tourbillon Universal Time 8126420 adds a tourbillon to the world time display in a 43.5 mm platinum case with a blue dial.