Rado True Round Thinline Les Couleurs Le Corbusier (spectacular ultramarine 4320K)

Spectacular ultramarine, shade 4320K, is one of the bold colours Le Corbusier added to his Architectural Polychromy in 1959, and it is the blue among the nine True Thinline watches Rado made from that palette in 2019, each limited to 999 pieces. The case and bracelet are high-tech ceramic in the same ultramarine as the dial, the case a monobloc 39 mm across and only 5 mm thick, and on its bracelet with a titanium clasp the watch weighs 80 g. There is no seconds hand: Rado's R420 quartz drives hours and minutes only, as Time+Tide pointed out when the series was launched. The titanium caseback carries all 63 Polychromy colours rather than a view of the movement, and the watch is rated to 30 m. Rado still lists the reference, now under the True Round Thinline name, at $2,400.

Written 10 October 2026 from Rado's product page, Rado's Les Couleurs Le Corbusier page, Time+Tide's 2019 introduction and C W Sellors' 2019 launch article.