Illusionists

If the glass jewel case is a trick, not only Kimberly would have to be in on it, but also the shop -- if indeed it actually occurred in the shop, and maybe even if it didn't, since the shop owners have been silent about it.

Yes, certainly the shop owners would have had to be in on it too.

I think the high degree of collusion required means that sceptics have a very weak case when they cite illusions like this to suggest that experimental parapsychologists would be easy to fool in the lab.