My experience:After all the experiences from my own submissions - the coins are usually also discussed here in advance - these definitions correspond best to me:
62vz+
63 xf-stgl (f.bfr.)
64 francs
65 f.stgl
66 stgl
s: 15-30
ss: 25-40
vz = 45-55
vz+=55-62
vz-st = 58-63
pr = 62-65
f.st = 63-65
st = 64-70
Each person grades differently and there is not an exact comparison between the US system and conventional German grading.