I think you should cleanse the crystal, and then work on enhancing it's natural energies. Energetically tie the two crystals together, then send him his. If you cast a spell to meddle with his thoughts and ideas then it may disrupt his natural self.
Linking the crystals together and holding onto them may be a more gentle way to lead him to you or you to him, perhaps. And both of you will be experiencing the vibrations of the paired moon opal, which will be good for the energy between the two of you.