Reference: al-Fataawa al-Muhimmah – Page 596;
Fataawa ash-Shaykh – Volume 2, Pages 719-720
Question: What is the ruling regarding selling gold rings specifically [made] for men to wear if the shopkeeper is certain that the [male] buyer shall wear it?
Response: The selling of gold rings for men is prohibited if the seller knows the [male] buyer shall wear it or he is sufficiently certain that he will wear it, because [the wearing of] gold is prohibited for the men of this ummah. So, if he were to sell it to someone he knows will wear it or was sufficiently certain that he will wear it, then he has assisted him in committing a sin; Allaah (‘Azza wa Jall) has prohibited this:
And it is not permissible for the goldsmith to make gold rings [specifically] for men to wear.