#sapphire caseback

A sapphire window on the back of a watch sounds like a small design choice. It actually tells you a lot about what the brand thinks its movement is worth showing off.

The 2026 Rolex Cosmograph Daytona Rolesium pairs Oystersteel with platinum, adds a grand feu enamel dial, and breaks Rolex's seven-decade caseback rule with a sapphire exhibition window. A working dealer's read on the most significant Daytona release of the modern era.