What is the ruling on men wearing yellow metals that resemble gold, such as copper and aluminum, and wearing white gold? And what is the ruling on men wearing what resembles silk, such as artificial silk and nylon?

It is permissible for a man to wear a ring made of any metal except gold, for it is not permissible for him to wear a gold ring due to the prohibition of the Prophet, peace and blessings be upon him, concerning that. If white gold is platinum, then there is no harm in wearing a ring made of it. However, if it is yellow gold that has been treated to become white, then it is not permissible to wear it. It is permissible for a man to wear artificial silk and soft or shiny clothing. The prohibition applies only to natural silk.