The Tatcha Violet-C Brightening Serum 20% Vitamin C + 10% AHA ($88) has more than 1,200 reviews and 77,000 loves at Sephora. If that's not enough to convince you, perhaps the fact that it has both a high concentration of vitamin C and an AHA blend of seven different fruits to exfoliate away debris and dead skin cells, both to brighten and smooth skin, will.