Be sure to Observe that commencing in 2005, Rolex started engraving the serial quantity about the inner bezel (also known as the rehaut) underneath the crystal in the 6 o’clock situation. When the crystals within the 160xx technology of Datejust watches are still made from acrylic, the sloped "pie pan" https://www.watchesworld.com/a-history-of-watch-reference-numbers/