You should receive the stone in the mail after completing the achievement. It is possible that it is taking longer than normal for the system to send it out. I'd agree with the others, submit a ticket either in-game or through the Support site.
Compromise is a basic negotiation process in which both parties give up something that they want in order to get something else they want more. Compromises usually occur in win-lose situations -- when there is a fixed pie to be divided up, and whatever one side gets, the other side loses.
The use of compromise will be most comfortable and acceptable when both parties in a dispute have a thinking approach to decision making based on their Myers-Briggs type. When mediating this type of interaction there may be a tendency for the parties to move quickly from a competing conflict mode to one of compromise.