i WANT to say it is Lanvin, but i could very well be wrong. But i do remember it being a big name designer. It was in an issue of US Weekly, cause Paris had worn it out like 3 times in two weeks.
i think it might be Marc Jacobs....NOT for Louis Vuitton, but his own label...the colors are the same as a long grecian style gown worn by Liv Tyler to the Oscars buring the year(s) that the Lord of the Rings was making it so big!