Recently I posted a group of manufacturing variations with concentric circles on chips. I just got a new one from Robert Eisenstadt. If there are others, I would be interested in getting one.

1 Smooth near rim- wide ring and circles in center with round edge.

2 Small circles near rim- wide ring with larger circles in center.

3 Smooth near rim- Narrow ring with circles in center.

4 Smooth near rim wth step down to circles in center.

5 Uniform size circles overall with narrow ring.

6 Circles on a small key mold.

7 Circles on a diamond mold.

I show a detail of the difference between the round edge of chip #1 and the square edge of all the others.