How to retrieve your IGG ID:
Open Lords Mobile;
Tap the settings (gear icon) on the lower right, then tap "Account";
Your IGG ID, a sequence of numbers, will be displayed there.
How to redeem:
Open the Lords Mobile top up page;
Choose the gem package;
Select a payment method;
Enter your IGG ID;
Complete the payment;
Wait for the gems to appear in your account;
If missing, restart the game to refresh your balance.