L, welcome to the DIY side!!
I'm away for a few days and we have a new thread and everything!!
I have a sample of Cosmojet and while it looked interesting on screen, it's quite strange IRL. The sides of the crystal are basically black but the top (the single flat surface other than the bottom) is clear. As in empty. As in you can see -inside- the crystal. It's very strange and I don't understand what the effect is meant to be but it doesn't sparkle or anything...
Anyway, Jet is beautiful and sparkly but not in a flash way. However, I think (Jet) Hematite would be amazing. I've been itching to do something with it for a long time...
I can't wait to see what you choose, I love new DIY projects even by proxy!!