Sobel Skin RX 35% Vitamin C Face Serum Sobel Skin RX 35% Vitamin C Face Serum ($105) takes on dark spots, dullness, and droopiness with three forms of vitamin C in one of the highest concentrations we spotted on Sephora's site. Unsurprising, the pro-level serum was actually developed by a dermatologist to improve skin's elasticity and tone, and deal with dark spots accordingly. Image Source: sephora.com Sobel Skin RX 35% Vitamin C Face Serum $105 from sephora.com Buy Now