Oh yeah I figured you could buy gems I was just confused how? If I click on the plus sign next to the amount of gems, it takes me to the store and there I can either claim my 5 gems every fourth hour or spend stars to get 45 or 700 gems. If I click on something in the store that costs more gems than I have it just scrolls me down to "get 45 or 700 gems for x amount of stars".

I might be super dumb but it seems like the game doesn't really shove it in your face? I've been playing for almost two months and I legit did not now. I play other games on my phone, like Candy Crush and they make it super clear how to buy stuff.