What is the ruling of Islamic law on finding a gold ring and being unable to search for its owner, and what must be done to avoid sin?

This ring is a found item (luqatah), and its finder must announce it for a full year in the places where its owner would inquire about it. It is permissible to appoint someone trustworthy to announce it on one's behalf. It is not permissible to benefit from it until after the year has passed.