OK. Silver then.
http://www.apple.com/pr/library/2013/09/10Apple-Announces-iPhone-5s-The-Most-Forward-Thinking-Smartphone-in-the-World.html
According to Apple: Gold, silver or space gray. You may want to consider space gray black and you may assume that space gray is black.
Put a space gray 5s that you call black next to a black iPhone 5 and you will see a difference. Space gray may have the black front, but the finish is most assuredly, not black.
My opinion and whatever you or anyone else wants to think or accept as understood is fine. But as for me, space gray is gray. Not black. Sorry.
iPhone 5 black on the left, iPhone 5s space gray on the right.
And if the correct term is grey and not gray then you got me. Sorry.