Cassandra Huysentruyt Grey of Violet Grey.

Some of Grey’s must-have products for this summer include (from left) Queen of Hungary Mist, Omorovicza ($90), a purifying neroli- and rosescented toner; Lid Tint in Dew, Jillian Dempsey ($28), a Violet Grey exclusive; and Wave Spray, Ouai ($26), a texturizing mist from celeb hairstylist Jen Atkin.