Safe Deposit Boxes

We are in the process of closing branches with safe deposit boxes.  Some of the boxes have member's that have moved away and will not be returning.  Does anyone have a process for this situation?  If we have the member mail us the key, sign a request to drill and mail them the contents was a suggestion, however, what if the contents can not be mailed safely?ie, diamond ringI have no experience in this..If you do, I can use your help.  Thanks