
Back when Cartier weren’t the watchmaking tour de force they are nowadays – before the seminal Tank saw the light of day – they were better known for their clocks, particularly of the mystery kind. It’s something that Cartier has in recent years been channelling into their mystery complications, but never quite as overtly as the Rotonde de Cartier Mysterious Day & Night.
The 40mm white or pink gold Rotonde case is already a thing of beauty with the signature sapphire cabochon a nice flash of blue on the crown. It’s the top half of the dial however where the main event happens, a complication inspired by their 1912 Comet Clock.

It’s hard to tell from the images, but the sun and moon indicator at the top is completely transparent. This is the mystery, with the golden celestial orbs poetically floating in the void. The sun and moon also double as hour indicators, pointing out the time on the 12-hour scale from 6 to 6.
The bottom half of the dial is reserved for minutes, useful given the slightly vague method of telling the hours. It also gives a distinct contrast between the classical Roman numerals and the contemporary Arabic 0-60.

The finishing, as you’d expect by now from Cartier, is immaculate, especially in the thematic guilloche radiating out from the centre of the dial. The rear is a little less ornate than some watches, but with the sun / moon indicator clearly visible you don’t need much else.
Price & Specs:
Model: Rotonde de Cartier Mysterious Day & Night
Case/Dial: 40mm diameter, white or rose gold case, guilloche finishing on the dial
Movement: In-house calibre 9982 MC, manual winding, 174 parts
Power reserve: 48h
Functions: Sun and Moon mystery indicator double as hour indicators, pointing out the time on the 12-hour scale from 6 to 6, bottom half of the dial is reserved for minutes indicated with a blue retrograde hand that travels from zero to “60” before jumping back to its origin and starting over.
Strap: Leather
Price/availability: $63,000
More details at Cartier.