Nickel commonly tones a color I affectionately call "pee yellow". You also frequently see nickels tone light powdery blue. These are the most common colors on nickels. Not sure why, but it is true in my experience.
ok... since we're showing off Matte Jeffersons... how about this one? sorry the pix are so dark. I can't wait until I get a decent camera!
1960's proof nickels tend to tone gold. here's a pic I've shown before. A regular war nickel, a violet toned proof, and a gold toned proof. and here's an MS Jeff... violet and gold