The Naturium Vitamin C Complex Serum ($20) is formulated with vitamin C, hyaluronic acid, and vitamin E. I use the serum every morning to brighten and add a little hydration — two pumps for my face, neck, and chest. It sinks into skin quick, leaving it plump and prepped for my sunscreen. A lot of vitamin C, especially those in a dropper bottle, start to turn yellow and oxidise. The Naturium Vitamin C Complex Serum uses a pump so you never really expose the serum to the outside world, which keeps it efficacious.