Gem Labs and Jewelry Certificates.

Materials and craft

“Jewellery certificate” is a loose trade phrase. Labs use more exact names. Common terms include lab report, ID report, grading report, origin report, and jewellery report. The name matters because each report has a set scope.

A gem lab tests the item sent to it. The test may name the gem. It may state whether the material is natural or lab-grown. It may note signs of heat, filling, dye, or other treatment. Some reports also give weight, size, shape, colour, or cut. A diamond service may give grades. Some coloured stones may receive an origin opinion when the lab offers that work and the stone is fit for it.

GIT runs Thailand's national gem and metal labs. Its online report check shows fields such as ID result, size, weight, shape, cut, colour, origin, gold content, treatment, notes, and test type.

GIT also states a key limit. Its online tool is meant to confirm that a report was issued. It is not a fresh test of the physical item. GIT says the tool covers items sent in from 1 July 2014, while some detail for reports from before 2024 may be incomplete after a system change.

Makers, trade, and place

The Gemological Institute of America, or GIA, has a lab in Bangkok. GIA says it does not certify or appraise the gems sent to it. It issues lab reports. Those reports give technical facts and findings. They do not state an appraisal value.

GIA's Report Check has a narrow role too. It lets a report number be checked against data in GIA's own records. This can show that the report data match the lab record. It does not prove title to the item. It does not judge the seller. It does not give a new value to the stone.

The same basic rule applies to other labs. The report must be read for the test that was done. An ID report may not give origin. An origin report is not an appraisal. A metal report does not tell the full story of each gem in a set piece.

The Asian Institute of Gemological Sciences, or AIGS, is based in Bangkok's Jewelry Trade Center. It offers gem and jewellery reports, origin work for some stones, and diamond grading.

AIGS also gives a clear example of report scope. Its Mini Report is an ID service with less testing than a full report. AIGS states that treatment is not checked for the Mini Report. This is why the phrase “has a certificate” can be too vague. Two papers from the same lab may answer different questions.