All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is permissible for women to wear rubies. As regards men, we have already issued Fatwa 90282 clarifying that it is disliked for them to wear it.
Of course, this ruling applies if wearing it is not accompanied with a corrupt belief, like believing that it prevents evil eye or magic, or prevents the harm of the devil, as in this case wearing it becomes forbidden.
A Muslim must believe that benefit and harm are in the Hands of Allaah only. Therefore, he is obliged to rely and have trust in Allaah, and it is not permissible for him to follow the means which are not religiously legislated or approved.
Instead, there are supplications and legislated mention of Allaah that are sufficient to repel such harms.
For more benefit, please refer to Fatwa 91008.