I think that's called black smoke? Or something like that. Kimlovescats has a kitty like this too, but she isn't longhaired like Chuck so the coloring isn't as obvious.

That is such a cool coloring. I've never seen it on a cat until I saw Emma(Kim's cat) and I think it is beautiful!

And I just love that big Chucky boy. Have I ever mentioned that I love the big hairy ones?