The 'So You Think You Can Dance' host splashed out on a very rare creation by the late designer a few years ago but admits she is yet to wear it out and is considering getting it stored in a safe place where she can still admire it.
She said: "It's the first piece of couture I bought. It's a tea-stained colour with whispers of spider web, net and tulle. It's the most beautifully exquisite dress. I haven't worn it to an event yet and, to be honest, I may never do so. I may just get it framed. Most of my friends have tried it on - they come round to my house and we drink champagne and dance around to Pavarotti while we take pictures of us wearing it. It was very expensive but it was in the sale and there were only two made."
Cat - who splits her time between London and Los Angeles - admits she's a fashion addict and often can't believe how many clothes she's got.
She told the Daily Mail newspaper: "My wardrobe is embarrassingly huge. I have Prada, Matthew Williamson and Alexander McQueen fighting for life. I have a walk-in wardrobe in my bedroom in LA, which has exploded onto three rails in my bedroom, as well as the laundry room and the guest bedroom. Then I have a room in my house in Hampstead that I use as a wardrobe, too. My friends and family always ask if they can go shopping in my wardrobe."