Take a look at the mid-point between the top of the ear and the "R" in REX. You can see a slight colour change showing contact and a touch of wear.
Look at the eyebrow, that colour change at the highest point is a slight touch of wear.
Nickel 'as a metal' is 10x tougher than silver and takes a bit of punishment before showing wear..
nickelsguy, Paulsz and Pacificoin probably got the grade right on this one.. Compared to me,.. they are the experts here..