Dravyaparīkṣā is composed by Thakkur (Thakkura) Pheru, not by Ācārya Nemichandra.

• Thakkur Pheru was a Jain scholar and an expert in practical sciences like gemology, architecture, astrology, and especially assay and money-exchange. His work Dravyaparīkṣā is a technical text about testing metals and currency.
• Ācārya Nemichandra (Siddhānta Chakravartī) did not write Dravyaparīkṣā. He is the author of Dravyasaṃgraha, Gommatasāra, Trilokasāra, Labdhisāra, etc.

So:

• Dravyaparīkṣā → Thakkur Pheru
• Dravyasaṃgraha → Ācārya Nemichandra