It's hard to get good pictures of a black comb on a black chicken!
But I think that's a single comb, so that would mean she's not a Sumatra.
She could still be just about any of the other breeds that people have been suggesting. The breed may become more obvious when she grows up-- some have combs that stay black, while some others stay red.
And of course, she may not be a pure breed at all. She might be some mix. If one of the Silkies was her father, she might have inherited the black skin from him