Thanks Nicolas for this information : it seems obvious now that two dials co-existed, but I had never taken few minutes to notice it before ...
Would you mind if I develop the list of open questions and also bring in some confusion ;-) ?
On my own DSA, which is 100 % original judging by the ravages of time, one can note clear discoloration from black to an homogeneous olive-green shade (which is, trust me, very attractive)
[URL=http://s1213.photobucket.com/user/karmin-watches/media/IMG_5241_zps124cf7a6.jpg.html][/URL]
I have never seen this shade on any other DSA, but am wondering whether the pigments used for coloring the scale could have differed from one dial to another ? I do not know whether the previous owner of the watch spent his life in the desert under the sun, but obviously the dial must have been, from day 1, different.
5 min markers have no lume, but are noticeably bright compared to the last circle on which minutes are marked (which into a colour halfway between the rail markers and the 5 min markers). We then have 3 different shades... Would that mean 3 different types of pigments ?
Sorry for confuision, but thanks for interesting investigation !
Karmin