Rolex use a steel called 904L for making the Rolex Perpetual watch cases due to its anti-corrosive feature.
There is a video on the Rolex site showing the case production process.
Image © Bip Mistry 2011
An amazing looking stainless steel Rolex Oyster Perpetual Datejust, one of the most popular gents Rolex watches along with the Rolex Daydate, also worn by ladies who prefer a large dial.
The watch has a ‘certified chronometer’ which means it has been tested by the Contrôle Officiel Suisse des Chronomètres (COSC). COSC was set up in 1973 as an independent Swiss organisation that certifies a chronometer under strict conditions which include different positions and temperatures.
Images photographer © Bip Mistry 2011