How do you get gems that you wont get for pre ordering?

Getting stoked for the game, and when I went to pre order I completely forgot about this. But you only get a certain “Pack” for pre ordering. So how do we get the other gems? I assume DLC, but how much are they planning to try and charge for this crap? I mean, I think Gems are cool but I really don’t want to have to pay a bunch of money for such a minimal part of the game. A character DLC is one thing, but gems seems to be pushing for cash a little too much.

Or do I have this completely wrong and is there some other way to get the Gems?