Glossary
Assay
The quantitative test that measures how much of the stated substance the material actually contains, usually expressed as a percentage against the declared or theoretical content, by a defined analytical method.
Why it matters on a certificate
Assay is the certificate's headline number: it says the material is what it claims, in the amount it claims. Because it is quantitative, "complies" is not an adequate entry; a reviewer expects a number with units and a limit beside it. Assay results also interact with impurities and water content, so an assay figure that is arithmetically impossible next to its neighbours is a consistency finding.
A worked example
A certificate reports assay "complies" with no number. For a quantitative test that entry cannot be compared against the limit, cannot be trended, and cannot support a reduced-testing decision, so the review records it as a finding even though nothing failed.
Examples are synthetic and illustrative; any limits shown are not the requirements for any particular material.
The COA Validator checks the element this term describes on every certificate it reads, and reports what is present, what is missing and what does not add up.