Diamonds are a special currency. They are bought outside of the game, with real currency. They allow you to buy some very useful or exotic items from the Diamond section of the Item Shop. Diamonds are owned by a player account. They are shared between all the characters on the account (cross-server).
The database DOES have a special item listed in the Item Shop, called 100 Diamonds, that looks like it was intended as a workaround for player-player diamond transfer, but it has never been seen in the wild.
100 Diamonds, that looks like it was intended as a workaround for player-player diamond transfer, but it has never been seen in the wild.