Slim elegance

YOU'RE looking at the world's slimmest perpetual calendar, one of the most complicated timepieces. A perpetual calendar watch is one fitted with a mechanism that correctly displays the day, date of month, year and often the moon phase. And the wonder of it all is the timepiece can self-adjust for the difference in days in a month and the leap year - the watch owner practically doesn't have to lift a finger to make it right, at least not in his or her lifetime.

The perpetual calendar timepiece you see here, Audemars Piguet's Royal Oak RD#2 Perpetual Calendar Ultra-Thin, is still fresh from the brand's research and development laboratory - and this concept watch is not yet available commercially.

Still, at only 6.3 millimetres in height, the RD#2 is impossibly thin for such a complicated timepiece and is hands down leaner than the thinnest perpetual calendar watches in the market today. Vacheron Constantin's Ultra Thin Perpetual Calendar, for instance, is 8.1 mm high, while Patek Philippe's new Nautilus Perpetual Calendar is 8.32 mm thick.

The RD#2, a follow-up to the Royal Oak Concept RD#1, which broke new grounds in the audibility of chiming watches, is of course slimmer than Audemars Piguet's existing perpetual calendar model (9.5 mm thick). But even when compared to the svelte models in the brand's less complicated collections, the RD#2 is thinner by far. The Royal Oak Extra-Thin, a time and date automatic timepiece, is 8.1mm thick; while the Royal Oak Self-Winding model measures 9.8 mm up.

RD#2 brings together two traits Audemars Piguet is famous for doing well - creating ultra-slender watches and perpetual calendars. In 1955, the brand produced the Reference 5516, the first perpetual calendar to feature a leap-year indicator.

According to Audemars Piguet, the biggest challenge it faced in producing RD#2 is "to re-engineer a three-storey movement into a single level, making it ultra-thin while combining and re-arranging functions to boost ergonomy, efficiency and robustness". The result is the "record-shattering" 2.89 mm Calibre 5133.

Based on Calibre 2121, the movement used in the Royal Oak Extra Thin model, the automatic mechanism, made up of 256 parts, took five years to develop. This indicates that the life of the project started around the time when the brand's chief executive Francos Henry Benjamin joined the company in 2013.

Despite the movement's slimness, there's no compromise in quality as the watch boasts a power reserve of 40 hours and frequency of 19,800 vibrations per hour, or 2.75 Hz. The watch is also hefty, notwithstanding its leaness, thanks to a 41 mm case and bracelet which are made of platinum.

RD#2 features a "Grande Tapisserie" blue dial that shows improved readability (over the existing perpetual calendar model) and expanded counters, including a night and day indication. The moonphase at 12 o'clock pays homage to Audemars Piguet's first perpetual calendar watch launched in 1955. W

BREAKING TRADITION

You only get to celebrate your 25th birthday once - and Audemars Piguet has taken advantage of the occasion to break with tradition and unveil two timepieces that depart from the original design to mark the 25th anniversary of the Royal Oak Offshore model.

The Royal Oak Offshore Tourbillon Chronograph, in pink gold or stainless steel, each limited to 50 pieces, is arguably the most radical re-design of the iconic timepiece since the brand rolled out the Royal Oak Concept in 2002. The 45 mm case - a first for the Royal Oak Offshore - gives the new timepiece a very robust feel. Encased in the watch is a newly designed in-house movement that's used to power past Offshore Tourbillon Chronograph models. The hand-wound movement has a power reserve of more than seven days.

"With a new architectural construction featuring sandblasted titanium bridges and satin-brushed chamfered edges, the movement looks as if it were suspended from the bezel," Audemars Piguet says.

The movement is exposed to the maximum through an open-worked dial to allow light to pass through it before hitting the sapphire case-back.

While the Offshore has gone through tweaks over the years, these were slight compared to the edgy and skeletal transformation in the latest Offshore Tourbillon Chronograph, which reveals not only a totally re-designed movement but also an entirely re-imagined dial and bezel. W