things to look out for
Shape of the crownguard,there is a slight "v" shape inside the crownguard.
on the Gen, the pin the crownguard have a small dent.
"Marina Militare" and the bars marking the seconds on the dial is laser etched into the dial, and not printet so it apprears slight copper'ish in the color compare to the "L SWISS L" at the bottom that are printed in white letters.
on the back, many of the rep's have not the correct "treefork", on the gen the bottom is filled out, on many reps this is missing
gen
rep
and the MM20 showen earlier is a rep, as it is not a Swiss 6497, but it seems to be a russian copy movement.
Gen
rep
last, if it is a gen there should be a 3 part box "inner, outer, woodbox" plus the 2 straps, extra buckel, extra tubes, cloth