This Rolex Day-Date reference 228239 is the modern 40mm form of the brand's flagship calendar watch. In 18k white gold it takes the line away from its usual warmth, and for a collector who wants the Day-Date in its quieter key, that is the point. Its self-winding caliber 3255 carries the calendar with date, the movement that marked Rolex's step into a new generation of efficiency and regulation. The case measures 40mm across and 11.8mm thick, a size that gives the Day-Date contemporary scale without losing its easy proportion. Against that cooler metal, the green Roman dial does the work, turning a familiar reference into something more specific. Rolex has spent decades refining the Day-Date rather than remaking it, and this reference shows how far the model can move while remaining exactly what it has always been.