Board Thread:Questions and Answers/@comment-11058446-20150927182044/@comment-7326455-20150928014100

Since you can't make a carved frozium until level 14, but can make a polished Air crystal (whatever it's called) at level 19, I'd be inclined to say that the Air region unlocks at around level 18.

I haven't the foggiest idea where the Water region might be, but there are Water crystals in the Jeweler menu, unlocked at level 30, so it's gotta be somewhere...