What is the ruling on selling cosmetics to women and selling hair dyes, specifically the black color?

Selling black dye is not permissible because it falls under cooperating in sin and aggression, as Allah Almighty says: "And do not cooperate in sin and aggression." However, if the seller does not believe that selling black dye is forbidden to someone who believes it is permissible, then there is no harm in it, though it is disliked. But if the seller believes it is forbidden, then it is not permissible for him to sell it.