Here are my thoughts and opinion, and please don't be offended because that is not my intention. I think that perhaps you should try to be a little more specific with what it is you are wanting. Crystal magic is fascinating, but it is also an immense topic that has more uses than I can even list here. Maybe you should do some research on your own and try to familiarize yourself with some of the numerous different aspects and paths connected to it, choose the one that interests you the most, and then start an intelligent discussion based on that. Good luck with your journey, my friend!
I personally love using Crystals in magic. I find it makes my spells stronger and stuff. They can be used for so much stuff, Astral projection, summoning, banishing, protection, psychic powers, anything really.
I think the beauty of crystals in magic is wonderful. They have the ability to be fit right in to just about any spell you want to amplify and direct energy depending on the stones. The first and most versatile being clear quartz.
But then the beauty of crystals and stones themselves outside of magical property that earth has givted us. Each with dazzling colors, patterns, textures, shapes. Right down to the way earth gives them to us. By lava or in the oceans sedimentary rock. Salt deposits in caves, veins of bright colors along rock walls. Crystals spiking around from clusters.
Ive loved and collected randomly 'cool' rocks since i could toddle. And still having that collection and being able to use what i already had without thinking to myself 'wow.what a pretty collection of something useless' to 'wow thank the gods i kept this, i can use this in something!' Is great.
Basically, I freakin love crystals.
Id go on about how much I love them for days if you let me.
I personally make use of crystals in a lot of my spellwork, my favorite stones for use are quartz, emerald, lapis lazuli, garnet, sapphire (in jewellery), aquamarine, moonstones, kyanite, agates and turquoise.