In 2004, a GH Research Institute test found that one plumper increased lip volume by an average of 3 millimeters. So we had high hopes that the five new ones we recently tested would rival — or exceed — those results. But our 25 volunteers, each of whom used one lip gloss twice a day for a month, were disappointed. Though many of the testers liked the glosses' texture (and some reported a moisture boost), our experts found that none of the plumpers measurably boosted lip size. So the original winner is still champion: City Lips Original Formula Lip Plumping Treatment ($19), an oldie but goodie.