There are multiple ways of earning Diamonds, including:

• -Collecting Diamonds from the Mini-Mine or Maximum Mine daily
• Completing Goals
• Joining a Tribe and working together to earn weekly rewards (maximum 20 Diamonds per week)
• Collecting bonus currency from Level 15+ Monsters
• Being ranked in the community-voted Top Islands
• Submitting a referral using the Submit Referral button in the Options Menu (once per account)
• Winning Diamonds from Spin Wheel
• Winning Diamonds from the Memory Game
• Logging into the game for three and ten days in a row
• Waking up the Wublins or Celestials who each produce a random currency with a chance at creating Diamonds
• Completing offers in the Free Diamonds menu (found in the Market Menu)
• Participating in the community contests on Facebook, Twitter and YouTube to win prizes