See the Two Fantastical Dresses That Literally Lit Up the 2016 Met Gala

No contest here: Claire Danes was Cinderella at the 2016 Met Gala. And it was Zac Posen who was responsible for dreaming up her sweeping pale blue masterpiece of a ball gown and bringing it to life. In true fairy tale fashion—that, by the way, was so in line with the theme "Manus x Machina: Fashion in an Age of Technology"—the dress lit up on the red carpet.

Woven with fiber optics, the custom Zac Posen dove gray organza gown was the result of "technology meets fantasy" sourced from France. It was truly magical at every single turn

Also magical was Karolina Kurkova's Marchesa masterpiece, which was designed by the design duo Georgina Chapman and Keren Craig, but powered by IBM. Yes, the tech company. The two brands joined forces to create a cognitive dress that exemplified wearable tech at its finest. How it worked: For every tweet that hashtagged #CognitiveDress, IBM's cognitive technology dubbed "Watson" analyzed, broke down the emotion or sentiment behind it (which was assigned a color), and lit up the 150 LED lights embedded in the 3-D flowers embroidered throughout the dress. (The following five sentiments were assigned: joy, passion, excitement, encouragement, and curiosity.) In Jeff Arn's words, the marketing manager of IBM's Watson, what we saw is "a dress that's reactive and responsive to what people are saying about it." We like to think of it as a mood dress.

Karolina Kurkova in a Marchesa dress with Graziela Gems jewelry.

Dimitrios Kambouris/Getty Images

"Marchesa is an emotional brand and I feel like this dress is reacting to emotion and it’s changing with emotion. At first what seems like a foreign idea actually seems like the perfect marriage now," Chapman tells us. "The normal perception of technology is far from the Marchesa DNA and in fact, creatively, it was an exciting project. We’re a brand of fantasy and what is more fantastical than technology and where it takes us."

Take a look at behind-the-scenes images of the making of Marchesa x IBM's #CognitiveDress.