This reference 6238 is remarkable for a number of reasons. Firstly, the dial has aged over time and 'turned' a light blue colour. This is due to the paint pigments reacting with the elements. A very limited number of Pre-Daytonas 'turn' blue, making this example very rare. Secondly, there is an underline underneath the Oyster Cosmograph signature, which Rolex collectors identify as a transitional period from 1963 to 1964, where Rolex switched from using radium to tritium. This dial is signed Swiss, which is correct. The bracelet is furthermore stamped for the fourth quarter of 1963, confirming the bracelet is original to the watch. The luminous on this example has faded evenly to a warm orange colour which matches the hands, further adding to the appeal of this watch. Overall, an exceptionally rare and crisp example.