Like All Rolex watches, the Oyster Perpetual Datejust 31 is roofed because of the Superlative Chronometer certification redefined by Rolex in 2015. This designation testifies that each watch leaving the brand name’s workshops has successfully gone through a series of tests performed by Rolex in its own laboratories according to https://www.watchesworld.com/11-of-the-best-womens-watches/