Magic Gloss to seal it together. The Magic Gloss uses UV light to cure/harden. I had to leave the necklace near a window for like a week (since we've had some really overcast days) to get it to cure. I'm sure you can use any other type of epoxy to get a similar effect.
A reader sent me this message when the original post Personalized Magnets posted. It has some great information:
Thanks Moonhopping for your great insight!
Did you give any handmade gifts for Christmas?