Boy, they sure do grow up fast!

Emma Watson, 18,  best — and, so far, only — known as Hermione in the "Harry Potter" films, has reportedly signed on to replace Keira Knightley, 23, as the official face of Chanel’s new fragrance, Coco Mademoiselle.

The deal- broken in an English paper, is reportedly 3 million pounds — almost $6 million — for a two-year gig. Some late reports have this mysterious new fragrance contract being denied by Chanel. We’re waiting for more details. You know how these muggles are, especially when it comes to wizardly fashion deals.

If it’s true, was Keira too old for a Mademoiselle gig? Or did Chanel get a bit peeved at how infrequently Keira actually wore Chanel gowns on the red carpets, instead favoring shredded chiffon gowns by Rodarte, like the one she wore, above, to the L.A. premiere of "Atonement."

Interestingly, a source told The Sun,  "Chanel has been dressing Emma for film premieres and parties in recent months to integrate her into the brand."

Let this be a lesson to Emma, who was born in France. Read the fine print on these fragrance ads! And keep wearing that double C!

Photos: Is it just me or is little Emma, at left, already starting to emulate Keira’s distinct red carpet pose, all hunched-shoulder/craned-neck, at right.

Posted by:Elizabeth Snead