Sapphire, an extremely difficult material to machine, is not often used in watchmaking. Hublot, however, has created no less than 500 Big Bang Unico Sapphire models cut straight from the stuff. This results in the wearer being treated to an uninterrupted view of the architecture of the Big Bang and Unico movement. The watch has a healthy 72-hour power reserve and is naturally water-resistant to 50 metres. The case middle, bezel and back of the 45mm Big Bang Unico Sapphire are cut from blocks of sapphire, while only a few pieces forming the spine of the watch are made from titanium: the screws, the crown, which is over-moulded with silicon, and the buckle. The skeleton dial, made from transparent resin, reveals all the gears of the Unico HUB1242 movement. Even the strap is transparent so that skin can be seen through it. Available as a 500-piece limited edition, the Big Bang Unico Sapphire is clearly worth seeking out.