Franoise Hardy wears the most expensive gold and diamond dress of Paco Rabanne, in Paris, France, in May 1968. Photo by Giancarlo Botti. Franoise Hardy wears the most expensive gold and diamond dress of Paco Rabanne, in Paris, France, in May 1968. Photo by Giancarlo Botti. RIP Franoise Hardy, age 80, French singer, fashion icon & muse to designer Paco Rabanne. The famed gold Rabanne dress she wore in 1968 weighed 20 pounds, contained 1,000 gold plaques & Franoise Hardy in a Paco Rabanne dress, 1968. Said to be the most expensive dress in the world at the time, it was made of solid gold and set with numerous diamonds ( The world's most expensive bag was unveiled at Paris Fashion Week: The 1969 Golden Bag