Stars have been stepping out in an assortment of sheer ensembles this summer, leaving varying degrees of something to the imagination.

Mad Men's January Jones, flashing her sexy side, donned a sheer black dress to an AMC cocktail reception honoring her show July 28.

Harry Potter's Emma Watson covered up partially in a sophisticated geometric frock while taping an appearance on The Late Show With David Letterman July 8 in New York.

Gossip Girl's Leighton Meester showed off her assets in a revealing jumpsuit at a Katy Perry concert July 28 in New York. And Transformers babe Megan Fox wasn't hiding much while visiting Letterman June 25. Count Ashlee Simpson and Freida Pinto in on the sheer madness, too. Simpson sported a dress with see-through panels at the Television Critics Association Summer Tour party Monday in Los Angeles. Pinto wore a sheer-topped frock to a London screening of Slumdog Millionaire Sunday.

Yes, it's eye-catching, and transparent garb can be gorgeous, as long as you keep it classy.

"The biggest mistake is not putting something underneath. Sheer is beautiful. You just don't want to be obscene," says Bobette Cohn, a fashion and celebrity stylist who has worked with Glenn Close, Ralph Fiennes and Molly Sims.

Her rule of thumb is simple: "I tend to put things undernearth so it's not totally see-through, like a skin-colored tube, so it looks smooth underneath," Cohn says. "You don't want to see bellybuttons or other details. You want it to look tasteful.

"It's most appropriate in magazine editorial, because you can airbrush out certain things. In public, probably it's most appropriate at night. When you have daylight behind you, it's very obvious what's underneath."

And the gauzy clothes can work on all body types, as long as they're styled correctly.

"If you had a sheer dress with a pattern, and if you had something underneath, it would camouflage and would not emphasize imperfections. It has to be flowy and sheer," Cohn says.

Stick with sheer pieces in a dark hue if you have a curvy figure, Cohn says. Lighter tones are suitable for slim body shapes, and prints are helpful in distracting from body imperfections.