IGI and GIA certification: how to read a lab-grown diamond's certificate
What an IGI or GIA certificate contains, how to verify a lab-grown diamond online, and what the laser inscription on the girdle says. The full guide.
Your stone's passport
A diamond without a certificate is a promise; a certified diamond is a fact. The certificate — or grading report — is issued by an independent gemmological laboratory that examines the loose stone, before setting, and records its measured characteristics: it is your diamond's passport.
IGI and GIA: the two references
Two names dominate world certification. The GIA (Gemological Institute of America), inventor of the 4Cs, and the IGI (International Gemological Institute), which has become the most widespread reference for lab-grown diamonds. Both grade lab-grown stones by exactly the same criteria as mined ones: carat, colour, clarity, cut.
What the report contains
A certificate states: the carat weight, the colour grade (D to Z), the clarity grade (FL to I), the cut quality, the stone's precise proportions, its fluorescence, a diagram of any inclusions — and, for a lab-grown diamond, the explicit mention of its origin ('laboratory-grown') along with, often, its growth method (CVD or HPHT). No ambiguity is possible: transparency is the rule.
The laser inscription and online verification
The report number is laser-inscribed on the stone's girdle — the thin band separating the top of the diamond from the bottom. Invisible to the naked eye, readable under a loupe, this inscription physically ties the stone to its certificate. Each report can then be verified online, free of charge, on the laboratory's website (igi.org, gia.edu): enter the number, retrieve all the characteristics.
At MICKAEL STONE
All our creations are set exclusively with lab-grown diamonds of documented origin. On our pieces with a significant centre stone, the diamond comes with its independent grading report: you know exactly what you are wearing.
Frequently asked questions
Both are recognised world references. IGI is today the most used for lab-grown diamonds, GIA is the historic reference: in both cases, insist on a report number verifiable online.
Are small stones certified individually?No: small-diameter diamonds ('melee', below roughly 0.20 carats) are not individually reported, whatever their origin. The house's rigour is what guarantees their quality and origin.
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