[glatt]

Looking at it again, Imma say it's black and blue.
The background is way overexposed. As is the dress. If you put it in photoshop or something and adjust the exposure, making it darker so the background isn't overexposed, the dress becomes clearly black and blue.

And then when you look at the original picture again, you see the black and blue.

Edit: I can't even see the gold any more. It's blue and black.