Well I made out this tut, enjoy. With this tut you can make things like these:
Impossible? nah.
Select a color and a shape
Paint it a white contour
Now draw some random lines, be as crazy as you want!
Use the paint buclket with a 25% opacity in random places that are limited by the white lines with the colors black and whit(so black for shadows and white for lights) you can use it in a place more than a time, it is better for the 3d effect
Use a white overlay in the places you want shiny
Use the airbrush to put a main light up.
Now the glowing!!
Use the airbrush with a white color in the contour
Overlay the last parts of the glow with white and the color you want it to glow
And finally use the smudge tool for making the glow look nice!
And so, you're done, enjoy making crystals!