It's definately black, but there's a rule when you're coloring things that are black to never use *black* itself, unless your working in greyscale, it's better to use a very dark colour such as brown or purple instead of say, grey. But in 3D, if you look at figures they don't have to do this because there's a real lightsource, so it's black!
(no subject)
Aha, I see this was cleared up ages ago xD;