Amid all the anticipation for Friday's Royal Wedding, the big question remains: What will Kate Middleton be wearing when she walks down the aisle and meets Prince William? "That is the biggest kept secret, ever!" one of Kate's former stylists, Nikki Pennie, tells Rachael. "I don't understand how they've managed to keep that [dress] a secret." Rachael asks the fashion pro what to expect for the dress, based on her experience working with Kate. "The dress will be very classic, timeless, chic and just very minimal," she suggests. "The whole focus will be on her natural beauty."

Kate already scored big fashion points with her hugely popular blue engagement dress. "Which was by my favorite designer, Issa," Nikki says. She worked with Kate on that outfit and notes that the dress was not couture or custom-made. Nikki says Issa dresses are generally affordable and quite versatile. "You can wear it to the office, to dinner - for your engagement!" She was not surprised that Kate chose something so accessible. "That's the thing with her, it doesn't matter how much something costs." And, Nikki praises the princess-to-be for her strong sense of style. "She knows what she likes and she doesn't follow any trends," she says. "It's just about comfort with her!"

Kate already has fans around the world who adore her style, including one of Rachael's viewers! Click here and see a royal transformation in a Kate Middleton makeover!