Earn free Diamonds on the game "Hay Day" by completing daily activities and special tasks, as well as leveling up and opening mystery boxes, as of 2015. Once you reach level 24, you are also able to mine your own Diamonds free of charge.
The online free-to-play game "Hay Day" allows users to simulate life on a farm through activates such as growing crops and caring for different animals. Part of it's free-to-play design is that certain items and powers in the game are only available if you spend some of the in-game premium currency, which are Diamonds. The easiest way to obtain Diamonds is to buy them with real-world currency through a debit or credit card, though the game does include multiple ways to earn them for free. For example, each time you increase your level, you receive a reward of one Diamond.
You can also receive Diamonds for performing special one-time activities, such as connecting your Facebook account to the game or Liking the game's Facebook fan page. The game also includes various achievements based on game actions such as farming and visiting areas. Earning these achievements rewards you with a free Diamond as well. The game also contains a special offers section that gives you Diamonds in exchange for watching advertisement videos.