Like All Rolex watches, the Oyster Perpetual Datejust 31 is covered through the Superlative Chronometer certification redefined by Rolex in 2015. This designation testifies that each watch leaving the manufacturer’s workshops has successfully gone through a number of tests carried out by Rolex in its own laboratories As outlined by https://www.watchesworld.com/11-of-the-best-womens-watches/