A matrix jewel or "starstone" provides a focus and a way to magnify "laran." In Darkover Landfall, a "chieri" gives one to his human lover so she can call on him if necessary. A matrix stone can be attuned to one person, who will always carry it with him and cannot lose it because he always knows where it is. If it is forcibly removed from him, he may go into shock and die. As related in "The Bloody Sun", a small matrix stone can be attuned to a person and used as a lock on a box, and only the person to whom the matrix stone is attuned will be able to open the box.