I fell in love with this dress from the Zara Christmas collection last weekend! It looks like a normal black sequin dress, but when you run your hands over it, the sequins flip over. Now as they're blue on the other side, this means you basically have three dresses in one! A black sequin dress, or if you rub the sequins so they're all turned round, a blue sequin number, of if you get creative, a black and blue patterned sequin dress (as above). Genius!