Released in 1972 and designed by Gerald Genta, watchmaking's most famous designer, the Audemars Piguet Royal Oak was the first stainless steel luxury sports watch ever to exist. Released as a tactic to survive the quartz crisis, the Royal Oak can single-handedly be thanked for AP's existence today due to its astounding success, albeit it wasn't an overnight hit. Its sizeable tonneau-shaped case, signature integrated bracelet, octagonal bezel, exposed screws, and steel construction failed to win over collectors until a few years later. Today, the Royal Oak is one of the most highly-coveted timepieces in all horology as its previously dismissed design details have permeated across the industry and into watches like the Patek Philippe Nautilus, Vacheron Constantin Overseas, Rolex Oysterquartz, amongst many other legendary timepieces.

Launched in 2018 as a concept watch before being officially released as a commercial offering in 2019, the Royal Oak Perpetual Calendar Ultra-Thin RD#2 is perhaps one of Audemars Piguet’s most impressive pieces of horological engineering in a long time. Made as a limited edition of 200 pieces, this titanium and platinum timepiece retains the Royal Oak’s famed construction in a modern 41mm diameter that stands just 6.3mm tall – a world record at the time of its release and 3.2mm less than a regular Royal Oak Perpetual Calendar. Boasting a unique blend of metals, this timepiece features a two-tone effect derived from platinum’s bright appearance, and titanium’s darker grey color in addition to the RD#2’s platinum parts being brightly polished and its darker titanium parts featuring a satin-brushed finish. In addition to this unique construction, the RD#2 also features a matte blue dial with a vertical satin brushed finish that makes it immediately distinct from other Royal Oaks that typically feature tapisserie finished, thus highlighting its status as a special watch amongst the Royal Oak family. Indeed, what makes it truly special is its ultra-thin automatic perpetual calendar movement, the cal. 5133. Standing just 2.89mm tall, it took AP’s best engineers to rework their cal. 2120 movement so that it features a floating barrel and a specifically-designed winding rotor with a specific construction that is supported by a beryllium ring and 4 jewels. Additionally, the cal. 5133’s 374 parts were redistributed so that its diameter increased from the cal. 2120’s 29mm to 32mm, allowing AP to make the movement thinner. A truly revolutionary timepiece from one of watchmaking’s finest brands, it is timepieces like the RD#2 that showcases how and why AP are as highly regarded as they have remained over the decades.