Jordin Sparks turned up to Muhammad Ali's Celebrity Fight Night XVI in Pheonix in a low-cut, lacy LBDand blinged-out purple polish. Metallic shades have a lot of impact on nails that are just a touch longer than the fingertips. Be sure to keep them roundedsquare tips can look too severeand scuff nail beds before applying polish to give the glossy formulas something to adhere too.