i saw this thing on one of those discovery channel type "odd stuff" shows, and it was a novelty item, for resale, the glass was originally designed for windows, but since they were nearly invisible, there were certain unsafe aspects to having windows that you could not see, (walking into them, not noticing if they are opened or closed etc...) so the project was scratched and they created misc items out of this glass one of them being that ball they said that it was so clear that if you forgot where you put it, you would have a hard time finding it, as a matter of fact, they has to use a special light so that they could film this thing for the show.