Achievements can be viewed from your Inn. A medal sits on top of your Inn when you have an achievement ready to collect.

Tap on the Inn and tap on the Achievements tab (the second tab down) to open the Achievements window.

There are three buttons for:

• Unlocked = Achievements you can accomplish at your
  current level.

• Locked = Achievements that require a higher level or
  having a certain item in order to accomplish them.

• Earned = Achievements that you've completed.

Unlocked: These are Achievements that you haven't earned yet. Read the description to see how to complete the Achievement. The Gem amount shown on the right is what you'll earn for completing that Achievement.

Locked: These are Achievements that you can unlock as you progress in the game.

Earned: These are Achievements that you have completed.Tap the Collect! button to collect your reward.