Hi,  first you need to go to the parent's center, that is the pencil looking icon that was installed with the game. Under the holiday tab, at the bottom there is a check box, mark that check box. When your child earns the gem, you can click on the mailbox to trade.

If he sees the award you made, that is what this feature is.  It is working correctly. By trade I meant that he could now print out the special award instead of the one the game generates.