Garudapurana 1.69.2

1.69.2

tatraiva caikasya hi mūlamātra niviśyate ratnapadasya jātu /
vedhyaṃ tu śuktayudbhavameva teṣāṃ śeṣāṇyavedhyāni vadanti tajjñāḥ //

And there alone does the basic qualification for the term ‘gem’ sometimes apply to a single [type]; / moreover, only those born from oysters can be perforated among them; the rest cannot be perforated, so declare those who know them.