Here is a color study of the 1851-57 Three Cent issue:

1851 - 1857 Three Cent Issue 1

1851 - 1857 Three Cent Issue 2

Excellent color studies of the 1851 issue can also be found at the following sites:

http://lonestar.texas.net/~mdr/st/ (Mark Rogers)

http://home.comcast.net/~3cent1851/color.htm (Gary Schrader)