(Cover) - EN Star Style - Emma Watson "just knows" when she's found the perfect red carpet gown.

The 21-year-old British actress has become a style icon of late, and regularly graces events looking impeccable.

The stunning star, who has modelled for luxury brands Lancme and Burberry, is instantly aware when she's found the perfect outfit for a premiere or high-profile event.

"It's really weird; you just know when you've got the dress on. I'm like, right that's it, no need to look any more, this is the one," she explained in an interview with OK! magazine.

Emma is the cover star of American Vogue magazine's July 2011 edition. The gorgeous star says working with the fashion bible and acclaimed photographer Mario Testino on the shoot was a dream come true.

"It's been my dream to be on the cover of Vogue since I was pretty much ten years old so it was ridiculously exciting, Mario [Testino] said when he shot me for Burberry, Darling, we've got to do Vogue together,' and I didn't take it too seriously," she recalled. "And then I get the call to say, Mario wants to shoot you for Vogue' that was bl***y exciting!" (C) Cover Media