Board Thread:Dragon City Gameplay Questions & Answers/@comment-11868147-20130710063111/@comment-10090661-20130802235228

That's correct.

To be eligible for the gems offer, SP says your friend must never have played DC before, and after accepting the invite, your friend must play the game.

In other words, you must introduce new players, and they must continue to play until your gems are awarded to you.

I think that your friend must play DC for several days (a week? two weeks?) or reach a certain level (10 maybe?) before the offer is considered complete.

If you feel that you have fulfilled the offer but are yet to receive the 5 gems reward, please contact SP for an explanation.