1) On your game's screen, select Skill on the bottom right corner
2) On the top bar, select the PLUS sign for the Diamonds
3) Click 'Top-up'
5) Follow the on-screen instructions for the respective payment methods and enter your Serial/PIN correctly. Please note that the blank spaces are case-sensitive.
6) Complete! You should have your Diamonds credited into your account.
Visit the SEAGM Support site for quick answers and guides.