I can mention that I have tried to use the old traditional LuckyPatcher, and doing so either doesn't work (faulty injection/altering of code) - or the few times that LP did actually do its job and allowed me to freely add/buy Gems to my account it got banned right after restarting the application.
As such, LP is not currently a viable option.
I imagine Keys are set on their Servers. I fear their Gems also are, but I don't have the skill/know-how to check.
Using LP definitely flags something, some measure of anti-tampering code in the application for certain.
PS - I would really like a modded apk for this, diamonds/premium choices would be more than enough for me.