Ask any beauty editor, and she’ll (somewhat begrudgingly) admit that the only way to truly tell if a buzzed-about makeup product works is to 1) try it yourself or 2) find it in the contents of a trusted makeup artist’s bag (even though a witty and well-written review can still give you great insight, ahem). Since the former is difficult when there’s rent to consider, we decided to ask ten Hollywood makeup artists for the one thing we can always find in their kit.