Returns a hyperlink for a permanently socketed gem. If the given socket contains a permanently socketed gem, returns an item link for that gem (even if a new gem has been dropped in the socket to overwrite the existing gem, but has not yet been confirmed). If the socket is empty, returns nil.

Only returns valid information when the Item Socketing UI is open (i.e. between the SOCKET_INFO_UPDATE and SOCKET_INFO_CLOSE events).