necklaces?.

[pink-peas.livejournal.com]

I'm pretty sure it was reebert But she posted some really beautiful necklaces with what looked like those marble magnets (= only without the magnet) it looked like she used it as one of the beads...but I was wondering how she got it on the string?... what kind of thing did she put on the back to make it able to string onto the cord?... and what kind of string would I use to make something like that ?
thank you!
<3
picture of it::