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20s

RACHEL BILSON, 28

The star's stylist Nicole Chavez says Hervé Léger has different cuts, so "you can find one that works with your body."

KRISTEN BELL, 29

"You can look sexy but demure in the knee-length ones," says Chavez, Bell's stylist.

HAYDEN PANETTIERE, 20

When Max Azria designs the Hervé Léger line, he says his goal is to "heighten and accentuate" a woman's shape.

JESSICA STROUP, 23

"It made me feel sexy, especially with the one shoulder strap," says the 90210 star.

ALEXIS BLEDEL, 28

Her stylists Kemal Harris and Karla Welch told PEOPLE this dress "is just like her: understated yet sexy."

LEONA LEWIS, 24

"Their fit is always incredible!" says the singer, who adds that the hot-pink number is a dress "I can dance in."

30s

LINDSAY PRICE, 32

This low-cut version "shows off Lindsay's youthfulness," says Price's stylist Amanda Ross.

JANUARY JONES, 31

"I like to see a woman with curves in this dress," says Azria. "It works so well with that shape."

GABRIELLE UNION, 37

The demure cap sleeves on this style downplay the short hemline's va-va-voom, Azria notes.

40s

ELLE MACPHERSON, 46

"I like to take risks with color," the supermodel has said, like with this bold raspberry shade.

STAR JONES, 47

After losing weight, Jones "vowed to tone up [enough] to be able to wear what I consider the sexiest dress ever made," she says.

50s

KIM CATTRALL, 53

Cattrall rocks her frock by projecting "attitude and confidence," says Azria.

SHARON STONE, 51

"She's in the best shape of her life—and isn't afraid to show it off!" says her stylist Kristi Brooks.

WHY THE DRESS WORKS

THE MATERIAL

The unique blend of rayon, nylon and spandex "makes the body form to the dress instead of the other way around," Azria says.

THE STRUCTURE

The different strips are "molded and sewn together" in such a way, says Azria, that the dress "maintains its ideal shape when you put it on."

THE PLACEMENT

Thicker bands are used to smooth trouble areas, while narrower ones keep curves from flattening out. "It's all done to flatter the female form," he says.