Laboratory accreditation is the formal third-party recognition that a gemmological or testing laboratory operates according to documented quality standards and is technically competent to perform the tests within its declared scope. Accreditation is distinct from registration, certification of an individual or membership in a trade association.

The principal standard

The relevant international standard for testing and calibration laboratories is ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories, currently in the 2017 revision. The standard sets requirements covering management, document control, personnel qualifications, calibration of equipment, traceability of measurements, validation of methods, control of test items, recording of results, reporting and continuous improvement. A laboratory accredited to ISO/IEC 17025 has been audited by a recognised accreditation body and demonstrated compliance across these areas.

National accreditation bodies are themselves typically members of the International Laboratory Accreditation Cooperation (ILAC), which operates a Mutual Recognition Arrangement (MRA) under which accreditation by one signatory is recognised by others. The leading bodies relevant to gemmological work include UKAS in the United Kingdom, ANAB and A2LA in the United States, DAkkS in Germany, and Standards Council of Canada (SCC) in Canada.

Application to gemmological laboratories

Many of the major gemmological laboratories carry ISO/IEC 17025 accreditation for specified scopes. SSEF in Basel is accredited under SAS, the Swiss accreditation body. GIT in Bangkok carries international accreditation. AGL is accredited in the United States. GIA and others have accredited components of their laboratories for specific tests.

Accreditation is granted for a particular scope of work rather than for the laboratory in general. A laboratory accredited for diamond grading is not necessarily accredited for emerald origin determination, and the accredited scope should be checked against the work being performed for a specific client.

What accreditation does and does not do

Accreditation provides a structural assurance of competence, calibration and quality control, but does not guarantee that any given grading or origin opinion is correct. Different accredited laboratories may legitimately reach different conclusions on borderline cases, and the resulting trade-level disagreements are addressed not by accreditation but by harmonisation efforts such as the Laboratory Manual Harmonisation Committee.

For trade members and for consumers, accreditation is one of several markers of laboratory rigour, alongside membership in trade associations, history of published research, transparency of methods, and the trade's own assessment of grading consistency. A laboratory that lacks ISO/IEC 17025 accreditation is not necessarily incompetent, but the absence is a relevant data point, and accreditation status should be considered alongside reputation and grading consistency in selecting a laboratory for a stone of significant value.