Speaking of magic in a box! This is a fantastic little set of fluorescent bricks. I'm using 365nm ultraviolet light and I see bright green, orange, magenta and yellow. My kids love it and want to see it again and again. I feel like I've brought the key element of any science museum into my home! Some reviews complain that the stone labels fluoresce so brightly that you can't admire them. That's true, but it's easy to turn the bricks over so the label isn't showing. This is not possible with a very flat transparent calcite, but it is nice to have labels for identification and provenance. ps This little calcite fell out of the box when it arrived so I thought I was missing a stone. It turns out to be so small and thin that it's easy to shake out, and I found it under the tray. So check carefully if you think you're missing out!