If the screen on which you purchase gems is blank, there are two common causes:
- We haven't yet enabled purchasing gems with Euros via credit card. (You can use Euros when purchasing via PayPal, but credit card orders must be in USD.) So if you have saved a credit card in your payment information, switch from EUR to USD in the lower left of that screen.
- Some players have encountered network problems preventing the screen from loading. As a workaround, try connecting via mobile hotspot for long enough to place your order or (if you have a laptop) taking it to a different network and connecting from there.