[JimMorrison]

Why not have it, but have it require 3 in the specific path?

I had always wondered, I mean your events say something like "The summer heat has been distilled into rubies by a young mage", things like this in the always made me feel there ought to be some way to make gems.

If the path requirements are higher, then the opportunity cost to make the gems ramps up immensely, and most indies would be incapable (mostly only a nation's best mages could do it). I see it more as a way to augment your income when you are very unlucky with sites, or to get into a path that you have no national income (and just need to generate some to start searching with).