I have a few Molnija pocket watches which I use as every day watches , but not knowing much about them I am asking if someone can help me. As far as I know the 3601 has 15 rubies and the central ruby has a brass casing just like the Cortebert movement . the 3602 has 18 rubies and the central ruby does not have the brass casing , the 3603 has shock protection but seems identical to the 3602 to my untrained eye. Can you tell me if my beliefs are right and also if there is a way to tell just by looking if a movement is a 3603 or 3602 if they don't have it stamped on. Thanks. Sorry for my amateurish way of describing the movements.