Description: Rolex Datejust 31 ref 278240 Pre-owned Rolex Datejust 31 ref. 278240 (2024). The Datejust has always been one of Rolex’s most versatile watches, and the modern 31mm series is a slightly more contemporary take on the classic formula. Larger than the traditional Lady-Datejust but still elegant and easy to wear every day, the Datejust 31 has become a popular middle ground for collectors who want something refined without feeling overly small or oversized