A tutorial would be beyond the scope of this website, but what I can tell you is that it largely depends on what engine you're using.
If you're using the Blender Internal renderer, you'll want to rely heavily on compositing.
If you're using the Cycles engine, you'll probably still do some compositing (for the glow) but in both cases, you'll want to work with the "Light Path" node to select which rays are actually visible in the camera. For example, if you give your crystals an emission material, then they will just look solid bright in the camera. However, if you set up a node system that doesn't show direct emission rays to the camera, then you can have the emission material cast light around the scene, but have the crystal look in the camera.
Take a look at the node setup on the SECOND answer on this question. The "Is Camera Ray" is piped into the Fac of a Mix Shader. This means that if the ray is directly visible by the camera, it will use the bottom shader and the camera will see a transparent material for that object. HOWEVER, if the ray is any OTHER kind of ray, it will use the top shader and the rest of the scene will see an emission material.
Exchange that Transparent BSDF for a really cool crystal-type material, and you'll see a crystal that casts light all over the scene.
The only problem with this setup is when the crystal is actually visible in the reflection of ANOTHER object. The emission shader will be visible in the reflection, not the crystal shader. So just be careful how you use it.
Hope that helps!