“Each model attempted to have logic of their numbering system but failed miserably,” Mandelbaum ongoing. “It just signifies the total absurdity in the Swiss wanting to think of a numbering system. While the crystals on the 160xx era of Datejust watches remain made from acrylic, the sloped "pie pan" design https://www.watchesworld.com/a-history-of-watch-reference-numbers/