Watch Of The Day: Franck Muller Vanguard Skeleton Sapphire

Your one-minute primer to the Franck Muller Vanguard Skeleton Sapphire.

Not content to show off the hand-wound calibre of the Vanguard Skeleton via an openworked dial, Franck Muller decided to let the light into the movement from all directions by housing it inside a full sapphire crystal case. Each tonneau-shaped case is hewn from a single block of sapphire that takes over four months to construct – two to machine the case, and another two to polish and finish it to perfection. This augments the visual intrigue of the timepiece, whose sublime airiness belies the structural strength of its flying tourbillon movement.