Common mistake with the term (chromatic vs. tone), 
but on top of that, I don't think that cel 
technically fits.  Heh.  I can relate because I 
had monochromatic cels as part of my cel panel 
recently, and I was surprised at how many of my 
cels were actually just night scenes (with a 
preference towards blues and blacks, but still 
containing different colors, like flesh tones) 
rather than true monochromatics.  I had to search 
quite a bit longer for a good example than I 
originally thought.

Pretty cel, though.  :-)

JP