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A certificate, or lab report, is an independent laboratory’s record of what a stone is: its identity, treatments and measurements. It is the best way to know you are getting the stone that was described.
Sri Lanka’s government authority for the gem and jewellery industry. Its gem testing laboratory issues reports that you can check online using the report number.
Identity
The species and variety, and whether the stone is natural or synthetic.
Treatments
Any heating, oiling, filling or diffusion found, or a note that none was detected.
Measurements
Carat weight, dimensions, shape and cutting style.
Colour
A description of the stone’s colour, sometimes with a trade name such as “pigeon blood”.
Origin
Where the stone most likely formed. Only some labs offer this, often as a separate report.
Report Number
A unique number and photo you can check with the lab that issued it.
GIA
Gemological Institute of America
Non-profit institute founded in 1931 and creator of the 4Cs diamond grading system.
Verify GIA reportGübelin
Gübelin Gem Lab
Swiss laboratory known for origin reports on fine coloured stones.
Verify Gübelin reportAGL
American Gemological Laboratories
New York laboratory specialising in coloured gemstone reports.
Visit AGL Gem LabGIC
Sri LankaGemmological Institute of Colombo
Colombo-based laboratory issuing identification reports for coloured stones.
Verify GIC certificateGGTL
Sri LankaGlobal Gem Testing Laboratory
Sri Lankan laboratory with an online certificate check.
Verify GGTL certificateWording differs between labs, but most reports use phrases like these.
Ask the seller
Request a copy of the report and its report number.
Check with the lab
Use the issuing laboratory’s verification service or contact the lab directly.
Compare the details
Compare the report with the listing and ask the seller about any differences.
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