To easily gain gems, open the "Friends" tab, then click the "Invite Friends" option. Enter another email address belonging to you. You will receive an OurWorld invitation. Click the "Go to OurWorld" link in the email to go to the home page, then click "Not a member" and join again. When you reach level 5 with your new avatar you will receive five gems. When your new avatar reaches level 10, you will receive five more gems. Transfer them to your main account. Repeat as desired.