Bejeweled blitz Colorblast and rarifier missing

[BlackRose0990]

I saw colorblast once and used it for a few min but switched back to my usual gems. After that I've never seen it again. I also just found out that there's another power up called rarifier that I've never seen. I'm rank 150 so surely my level isn't too low to get it. Why can't I see them?