do you collect them just for their beauty, or do you use them for some kind of energy work?

BOTH? Seriously, the latter. Energy work. It helps with my spiritual journey too. The raw and high quality the crystal is, the more potent energy it stores. I used to buy standard ones now I shifted on buying high quality ones. I just had a crystal bracelet arrive yesterday, its worth 6.5k. 😅 and I don't regret it.

I already made a post about it: Discover the Magical World of Crystals!. I will still have to do a follow-up post since my collection is growing.