Ah, yes, that's the best, rubbing your fingers in graphite.
My mother always wonders what's happened to me when I've been drawing, because the tips of all my fingers, and the edge from my pinky to my wrist are all silver. It's so successful when you do it, though; I love it, because I usually use it to make things darker and smear lines as opposed to add variation to people's faces, and all, but it's so beautiful when you do.
And thank you very much. It means a lot to me that you think so, and that I could learn. I'd like to try.