quality certification; hallmark
Used for official marks or certificates that verify the purity or quality of precious metals such as gold, silver, or platinum.
This ring has a hallmark stamped on it.
The gold bar comes with a quality certificate.
刻印 is a general term for an engraved mark or seal, while 品位証明 specifically refers to a mark or certificate that certifies the purity of precious metals.
Compound of 品位 (purity, quality) and 証明 (certification, proof).