I guess that makes more sense. War of Diamonds (or Crystals) sounds cool and prevents people from becoming OP. What specific type of magic do the diamonds have, though?
well...that would depend. If they're used as more of a focus - say an amplifier, it would simply make any magic used through it stronger.
Now, if they store magic or something, then they would hold whatever magic that was last stored in them.
Obviously, the larger and purer the diamond, the more powerful it would be as well.
Keep in mind, I haven't really put that much thought into these ideas, since I've only been up for about an hour or so...so yeah, feel free to add stuff/flesh them out yourselves....xP