Beyonce name drops it in her songs. Rappers wear them. And Shah of Iran was the first to buy it. Whether you’re a serious watch collector or simply love watches, a Royal Oak by Audemars Piguet is bound to figure in the mix.

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Surprisingly, the model by the Swiss maison (still one of the few independent companies owned by the founding families in the industry) took a while to kick off when it debuted. Launched in 1972, it was conceived by well-known watch designer Gerald Genta in just a day, and intended to be a stainless steel luxury sports watch at a time when sports watches were anything but that.

Its distinctive octagonal bezel was inspired by a diving helmet (an apt inspiration for a water-tight timepiece). It also spawned a series of best-selling models, including the Royal Oak Offshore chronograph, which remains one of the most popular watch models around.

Which is why the limited-edition 50-piece run the brand designed for The Hour Glass is one desirable timepiece. For one, it’s18K yellow gold look and forest green dial is a palatable throwback to the ’70s. Then there is the discreet 3.05mm case which hides an automatic movement but does not scream “towkay”. The final collector’s touch: the “The Hour Glass” and “One in Fifty” inscription on the oscillating weight on the case back of the watch.

Audemars Piguet Royal Oak Extra-Thin The Hour Glass 18K yellow gold watch, price upon application, The Hour Glass

Like this? This singing bird cage by The Hour Glass is another perfect SG50 tribute