If you want to purchase an item and you don’t have enough coins, you are able to do this directly from the shop page. 

• Tap the item that you want to purchase with coins and confirm you want to buy it. 
• If you have enough coins, the item will be purchased instantly. 
• If you do not have enough coins, you will be prompted to convert some of the diamonds that you have to coins. 
• If you do not have enough diamonds or coins, you will be prompted to buy diamonds. 

Diamond to coin conversion is no longer available in the Gift Shop.