I have a Peruvian opal rough cut semi precious stone necklace that I have been attempting to re-string.  I have made several attempts to remove the old string only to have the string stuck in the middle of the stone and it cannot be removed.  Can anyone advice me how to remove string from the middle of my beautiful stones?

Many thanks in advance.

 Get a drill bit a little smaller than the hole, attach it to a drill and run it through the hole. I would drill just a little, pull the drill bit out and remove any thread stuck to it and repeat untill the hole is open. Should be no problem.

Thanks Shanks.  Never thought of that.  I appreciate the quick advice.

 Did you get the holes open?