Audemars Piguet, one of the marquee names showing at this week’s SIHH Geneva watch fair, is on a roll. The Le Brassus brand has let fly with a barrage of launches, including more than a dozen variants on the original tough-guy watch, the Royal Oak Offshore, a design that was first shown 25 years ago and whose arrival sparked a seemingly unstoppable move towards ever larger watches.

The Royal Oak RD#2 Perpetual Calendar Ultra-Thin

But for 2018, the pick of the maison’s new collection is an ultra-slim version of the original Royal Oak, the revolutionary steel design that created the sports-luxe watch category in the first place.

Where the Offshore took the design into a testosterone heavy space, all technical cuts and edges, the RD#2 pushes the design into a more contemporary, less strident place with a barely-there case that houses a perpetual calendar movement within a mere 6.3mm height. 

This is right at the limit of what’s possible with conventional materials, the problem being to keep the whole structure stiff, any flex would affect the working of the watch.

Impressive a feat as it is to fit such a complex mechanism within such slender dimensions, the real magic is in the way that Audemars Piguet masters the fine details – the precise angle of the polished facets on the bezel, the clean feel to what is an incredibly busy dial (there’s a moon-phase to go with the years, months, days and date displays). Beyond all that, the watch remains instantly recognisable – it’s a Royal Oak from any angle.

Audemars Piguet is not the first watch house to take sports-luxe in a super slender direction: Bulgari’s Octo Finissimo for one (a design that shares its origins in the mind of the great watch designer Gérald Genta, creator of the Royal Oak), but the RD#2 demonstrates the value of having that rare thing - a genuine masterpiece as a template to work on.