That was discussed a lot in the Yennefer thread, maybe you should take a look there.
CDPR officially stated in this forum that the hair IS black indeed
So we can trust them, I think
They've heard that many players are concerned about the color, so they will take care of it.
And a short explanation about the black/brown discussion:
Most of the natural black hair looks brown under direct intensive sunlight. There are proofs of it in the Yennefer thread.
Thanks for the info, but I still don´t buy the sun or lighting thing, black hair is black, another thing is if you have dark hair, I have dark brown hair, and it looks very dark unless with a bright light like you said, but any guy or girl I know with really black hair, is black, no matter what, the colour doesn´t change.
Sorry if I sound a little arrogant, I just want to make myself clear in my opinion, but again, thanks for the answer and the info.