Praise be to Allah.
Selling gold rings to men, if the seller knows that the buyer is going to wear it or he thinks it most likely that he will wear it, it is haraam to sell it to him, because gold is forbidden to the males of this ummah. So if he knows or thinks it most likely that he will wear it, then he is helping in sin, and Allaah has forbidden us to help one another in sin and transgression, as He says (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression”
It is not permissible for a goldsmith to make gold rings to be worn by men.