con⋅trast –noun: opposition or juxtaposition of different forms, lines, or colors in a work of art to intensify each element's properties and produce a more dynamic expressiveness.
So therefore good sir, contrast can be "black on black" as in gloss black on flat black, or in the case of my VX, the gloss black compared to the almost black cladding. It does need to be "light and dark" as you may be thinking, although, that is likewise considered "contrast".
Bart