Slice cucumber. Chill the slices. Wash your face. Close your eyes.
Place the chilled cucumber slices over and around eyes. Relax for a
few minutes. Gently rub the slices on dark circles and dark spots.
Wash your face again.
You can also apply cucumber juice or potato juice on the dark circles
or dark spots on face with the help of cotton for about 20 minutes.
http://severaltips.blogspot.com/2008/10/dark-circles-under-eyes-dark-spots.html