How do you get free runes of magic diamonds

Matters what you mean by free. If you mean completely free (no gold OR money) You go on the main site you can do surveys for free and receive small amounts of diamonds. If you just mean no real money, you can purchase diamonds from other players (well not the diamonds, but the required item, this is done by the diamond seller gifting the item needed, then you mail the amount of money needed). WARNING, this is done based on trust. I would look around your guild to see who is trusted and who is a scammer. If you are on Govinda, DO NOT buy from a player named Cyongarr. Please, he is a well-known scammer.