"Roulette Date" appeared on the first Rolex Datejust model back in 1945. It got its name because of the alternation of black and red numbers, similar to playing in a casino 🎰 

Initially, even numbers were red, and odd numbers were black. In modern versions, the opposite is true: odd dates are red🔴, even dates are black️️. 

Officially, Rolex does not use the term “Roulette Date”. Instead, they call this style a “Two-color date Display”.