I picked up this 1918-S Standing Liberty quarter up the other day. It appears to have AU58 or even MS details, and although it has mint luster, it was obviously cleaned at one time. How would you grade it?
I don't see the cartwheel effect. I believe the darkening at the top of both images is the result of the positioning of the lighting (from the 6 o'clock direction).
The pictures were taken with a basic Sony digital camera under fluorescent lighting. The obverse picture was taken with the light source at 6:00, while the reverse shot was taken with the light at 12:00. The cartwheel effect is easier to see under natural lighting.