Single crystals of cobalt ludwigite Co3O2BO3 with diamagnetic substitution of Ga3+ ions for a part of the cobalt ions have been grown by the flux method. A detailed investigation of the crystal structure and magnetic properties of the compound has been carried out. A preferred character of the occupation of nonequivalent crystallographic positions by gallium has been revealed. It has been found that the effective magnetic moment and the magnetic ordering temperature are decreased compared to those in the original crystal of the Co3O2BO3 ludwigite. It has been noted that the pronounced magnetic anisotropy observed in the crystallographic ab plane of the original material of the Co3O2BO3 composition disappears in the presence of gallium.