Counteract any colour harshness with Amika's Bust Your Brass Cool Blonde Conditioner ($24), an ultraviolet conditioner that balances out brassiness in blond or grey hair. The product also deeply nourishes with shea butter and keratin, so colour-treated hair stays soft and shiny, too.
(There's also a partnering Bust Your Brass Cool Blonde Shampoo ($20) that tackles hard water buildup while also offering vitamin- and mineral-rich additives like avocado oil.)