To request a refund on a inadvertent purchase you will need to contact Apple, since the purchases are made through iTunes.
Here how to submit a refund request:
1) Find your in-app purchase records. Check your email for iTunes receipts or use a computer to sign in to your iTunes account and view your Purchase History. Here is a link that will help you locate your in-app purchase records: http://support.apple.com/kb/ht2727?cid=CDM-US-DM-P0015957-321943&cp=em-P0015957-321943&sr=em
2) Use this link to submit your refund request to Apple. https://getsupport.apple.com/ServiceOptionAction.do
3) Provide the requested information and enter "Refund" in the Details section
4) You will be prompted to send Apple a support e-mail; please let them know what happened and that Pocket Gems approves this request for a refund.