Here is my recently acquired Diastar 2.





Note the brushing on the steel portion of the case. Also note that the caseback started as a Diastar 2 but had a /1 engraved at a later date. It is a screw back, not bayonet, and the watch is powered by an AS 1858. I initially believed this to be an ealier DS2 but apparently it is a late version.





The watch is 40mmin diameter and, Mike, it is significantly thinner than a regular Diastar. My Diastar8/1 is 12mm thick and the DS 2/1 is a mere 10mm thick. In light of this perhaps the flat crystal is correct and the 2/1 was intended to be a thin watch.