The Hublot Big Bang Unico Sapphire watch reveals all of its inner workings in a transparent case, which is cut from blocks of sapphire. Usually reserved for limited editions, sapphire is an extremely difficult material to machine, yet never one to shy away, Hublot has made 500 models to introduce to the market. The case middle, bezel and back on the Big Bang Unico Sapphire are cut from blocks of scratch-resistant sapphire, a material that is almost as hard as diamond. Its skeleton dial - one of the few parts not made from sapphire - reveals all the gears of the Unico HUB1242 movement and automatic flyback chronograph, which has an approximate 72-hour power reserve. Completing the ethereal silhouette is a transparent strap that is all but invisible on the skin. With a minimalist style, this Hublot watch really has nothing to hide.