What's sizzling (and what's fizzling) on the red carpet.

Michael Stewart/Wireimage; Gilbert Flores/Broadima

In our weekly roundup of the looks that are gaining fashion ground (and the ones losing their style street cred), we saw some delicate digits, a tricky, trendy hairstyle and a collar that can be stashed away until winter.

Up: Light Blue Nails. We usually associate blue fingertips with the cold, but this cool trend is only getting hotter by the minute. Style Council Member Jamie Chung opted for a light blue lacquer to go with her edgy outfit at a screening of Only Lovers Left Alive in New York. While she demonstrates that the trend is perfect for a dressed-down ensemble, actresses Emma Roberts, Lena Dunham and Drew Barrymore paired their red carpet dresses with variations on the hue proving there’s really no wrong way to wear it. With the endless selection of shades, we hope to say goodbye to black, wine and grey and hello to robin’s egg, powder and baby blue.

Up: Faux Bobs. Two of our best-tressed celebs joined the “bob brigade” this week — temporarily, at least. Lea Michele tricked us into thinking that she had chopped her brunette locks, but upon closer inspection, we notice that it’s merely an updo mimicking the popular trend. Kate Upton went for the same tucked-under ends for a sweetly retro vibe at The Other Woman‘s premiere. And finally, Kaley Cuoco also had us fooled this past weekend on her Instagram with a picture captioned, “I can’t stop!” We think this is a great way to try the trend before committing — wonder if any of these stars actually will go short?

Down: Fur Collars. Is it hot in here or is it just Rita Ora’s collar? The singer sports a fuzzy topper on her Roberto Cavalli gown, but we think she’ll really be sweating once she realizes that we won’t be seeing this look for a while. Now that the weather is heating up, we think it’s time to pack it up and make way for spring favorites like embellished and Peter Pan collars.

Even more red carpet trend reports:

–John Soper