We have investigated ligand-stabilized Au-55 clusters by means of scanning tunneling microscopy (STM) at room temperature on highly oriented pyrolytic graphite (HOPG) and other substrates. Single clusters or groups of several clusters were transferred between sample and STM tip using conventional voltage pulses. With a new variant of voltage pulses called "field-emission pulses", cluster shells were partly destroyed by heating with the field-emission current, resulting in a "hardening" of the cluster layer. HOPG substrate surfaces with most of the clusters removed exhibit "pearl chains" of clusters attached to step edges.