The full-size Fifty Fathoms, with a date you can read.

Fifty fathoms is about 91 metres, the depth Blancpain’s 1953 watch for French combat divers was built for, and the rules it set, a one-way bezel, a screw-down crown, a dial you can read in the dark, became the rules for every dive watch after. The current 45mm case keeps the proportions and adds the sapphire bezel, the scale sitting under a domed crystal so it cannot scratch, and the 6918B, which runs five days on its barrels so a week off the wrist does not stop it.

The Grande Date is the version for people who found the standard date too small on a dial this size. Two discs sit under one window at six and the digits are as tall as the markers. Everything else is the Automatique: the big 12, the darts, the red-tipped seconds and the sail-canvas strap that the Fifty Fathoms has worn since the revival.

This is a regular Amazon listing from a marketplace seller with Amazon’s 30-day return window; it is not a Luxury Stores unit and the seller has not published a condition. The second button opens the live search for Fifty Fathoms Grande Dates in case this one has sold.

Fifty Fathoms have resold for under new and close to what pre-owned buyers paid, sometimes more, sometimes less; that is a pattern, not a promise, and nothing here is investment advice.