Bought this the other day and the diameter is right @- 29.4mm but the weight is off a@ 10.62 Grams.
I think it is 1789 KKM#586.8 (Bordeaux), but on the reverse there are a couple of differences:-
1- To the right of the date is a circle not a star
2- Before and after REX is a dot.
Are these differences specific to that mint?


Thanks
Stewart
