I would just point out on a positive note with regard to earnable gems, the recent goals rework injects another 20,000+ earnable gems into the overall economy. That means between goals and story mode there are now approximately 50,000 earnable gems through regular play. Not only does this help with some of those glyph aquisitions but also helps pay for participating in events to earn Diamond marks.
To the original question, you cannot buy these gems; you must earn them through playing the game. Nothing is perfect but at least on this point it is not p2w.
