Cult Following

Youth serum

Jean-Louis Sebagh's skin-care line used to be available only to his patients (that loyal circle willing to wait 14 months for an appointment in his Paris or London office). But now the good doctor has released his anti-aging products to the world. Sold at Space.NK in London, Sebagh's formulations—like the Pure Vitamin C Powder Cream— are some of the most potent we've tried. "I made it with a twenty percent concentration of vitamin C," he says. "Otherwise, it would be a gimmick." $95-$135. 44-20/8740-2085.

—Ann Marie Gardner