For the 1871 half penny there are two die varieties.   The differences can be noted in the date.

Black's Guide 2
Mont Orgueil
From "Black's Guide to the Channel Islands" by David Thomas Ansted, 1870


1871
Half Penny
Obverse
Reverse




The spacing is measured between the eight and the seven.


Obverse Dies:  The Date


Small spacing between the 8 and the 7.



Large spacing between the 8 and the 7.