Why a display back

A case back you can see through costs a sapphire, six screws and a gasket that has to hold at a hundred metres. For most of a watch’s life nobody looks. We made the Forty’s back open for the minute someone does.

What you see

The rotor first, because it moves: a rhodium plate on a tungsten rim, turning with the wrist. Under it the bridges, striped and bevelled, the blued screws in their sinks, the rubies in their chatons, and at the edge the balance, swinging four times a second.

Every one of those finishes is done for the back. A closed case would have let us skip them. The display back is a promise that we did not.