ʻO nā papa hoʻololi metala he mea kūpono ia no nā papahele sima paʻakikī, a i ʻole nā papahana ʻoihana me ka paʻakikī Mohs ma luna o 6, hiki iā ia ke wehe pono i nā ʻōpala i waiho ʻia e ka wili metala, e hoʻololi pono i nā hana polishing a hoʻomaʻamaʻa i kou papahele.