The dress is actually Blue and Black… but, when the photo was taken, the camera made it “hot” so the filtering of the color of the dress turned it into this gold color. Happens all the time with runway photography. Under hot lights, the models have a goldish hue. But once you auto-color (or turn on the cooling filter in photoshop) it turns it back closer to the color it should actually be.
No one here agrees though so take what I’m saying with a grain of salt.
Here’s a runway photo as an example: