white & gold 
or is it 
blue & black?

Pix11.com collaborated with my own hypothesis that the dress was indeed blue and black. There's a lot of scientific mumbo-jumbo to explain it (mostly from what I could tell had to do with lighting and how the eyes perceive color), but it all comes down to the facts. The actual dress, which is a Roman Originals, is sold on Amazon (click
here to view the actual dress in it's unaltered form) and truly is
royal blue and black.

Update: the company that designed and sells the dress, Roman Originals, has confirmed via their official Twitter account that the dress is in fact blue and black.