The game has traditionally treated the currencies as interchangeable insofar as players with lots of Diamonds and not enough gold could sell their excess to other players. Unfortunately, the current spate of RMT activities have called for draconian measures: they've taken away the ability to trade Diamonds for gold. They've also temporarily removed the ability to send gold through the mail. The official announcement stresses that this is a temporary measure to combat unacceptable behavior. While less gold spam is a good thing, fewer features are a negative, so this new is a mixed bag for Runes of Magic players.