Blackstone is exploring a sale of medical-grade skincare company ZO Skin Health that could value the business at around $2 billion, people familiar with the matter said. The investment firm is working with Citigroup and Raymond James on the early-stage process. ZO, founded by dermatologist Dr. Zein Obagi in 2007, sells cleansers, serums, exfoliators and toners through physicians and skincare professionals. The process comes as strategic buyers prioritize clinically backed, physician-distributed brands, which are viewed as offering efficacy and steadier demand than over-the-counter products.