Because there's an intense light shining down on it and the exposure is way off. Pure black dye does not actually exist, usually it's a really dark brown. Under the kind of intense lighting in the photo it appears brown (or gold if you will).
What he is asking, is how can you see what appears brown as black? They are talking about the colours of the image.
But I have see both. It has looked very black and blue once, and very white and gold.
Although, I mostly see blue and brown.