तपनीयं ज्येष्ठं सुवर्णं सुरागं समसीसातिक्रान्तं पाकपत्त्रपक्वं सैन्धविकयोज्ज्वालितं नीलपीतश्वेतहरितशुकपत्त्रवर्णानां प्रकृतिर्भवति ॥ कZ_०२.१३.४७ ॥
tapanīyaṃ jyeṣṭhaṃ suvarṇaṃ surāgaṃ samasīsātikrāntaṃ pākapattrapakvaṃ saindhavikayojjvālitaṃ nīlapītaśvetaharitaśukapattravarṇānāṃ prakṛtir bhavati
‘Tapanīya’, the superior (jyeṣṭha) gold—well-coloured, processed beyond (the stage involving) equal lead, matured by heating in thin layers (pākapattrapakva), and fired with a saindhavika additive—yields the natural basis for colours such as blue, yellow, white, green, and the hue of parrot-feather.
It gives inspectors practical criteria to verify whether gold meets state-defined grades, which protects revenue and prevents counterfeit or under-standard bullion.