If you talk to the bank teller in Arnika she will
tell you about the bandits who robbed the bank and
made off with the diamond. If you return it to her
she will give you a small reward in gold and exp.
If you are only interested in the gold, you are
better off selling it to a merchant. (Just make
sure word doesn't get back to the teller).One of the silly points of this game is if you hostile
the bank teller/guards by picking her pocket or
robbing the bank, the other Higardi will come to
your aid in battling the guards. Apparently all
the factions in town have no relationship amongst
each other and are driven only by their allegiance
to your party.