Got one of these and it pretty much worked as advertised.

Final version of the crystal

This is after about three weeks of leaving it unattended.

The beginnings of crystal formation

I was pleasantly surprised by how it turned out, because we didn’t stir it too well, and didn’t really “arrange” the stones at all, and we were expecting it to be just a bed of crystals at the bottom.

An intermediate version with “one tree” done growing

In the beginning nothing happened for the first week, but then it ended up “growing upwards”, a bit more every day, which was fun to watch!

I think we’re going to check out more adventurous versions of this now, maybe combining colors?