Wang discusses the fabulous garment on an episode of CNBC's "Conversations with Michael Eisner" set to air Monday.

Asked what the most expensive wedding dress anybody has ever asked her to design was, Wang told Eisner: "Probably the most expensive -- dress I have ever done was a dress that -- actually didn't get worn at the wedding but was (designed during) -- Jennifer Lopez's first engagement. Engagement, wow, it's really -- her -- yes, it was her engagement to Ben Affleck."

Wang didn't reveal the price, but said it was "the most expensive dress" because it was made of couture fabric and had 18 tiers.

"It was really, probably far and away, the most expensive and time-consuming to sew," the designer said.

Not long after the couple called off their wedding, Lopez married singer Marc Anthony, and has since become the mother of twins.

Affleck married actress Jennifer Garner and the couple have one daughter.