Diamond Certification: How GIA and IGI Reports Work
A diamond report tells you what a stone is, not what it is worth. Here is how GIA and IGI reports work, what sits on the page, how to check a report is genuine, and what honest lab-grown labelling looks like, so you can compare diamonds with confidence.
What a diamond grading report actually is
A diamond grading report is a document from an independent laboratory that describes a diamond's quality. It records the 4Cs: cut, colour, clarity, and carat weight. The 4Cs and the grading system used around the world were created by the Gemological Institute of America (GIA), a non-profit research institute.
A grading report is not an appraisal. It does not put a dollar value on the stone. It describes what the diamond is, using fixed standards, so you can compare one stone to another in a fair way. If you need a value for insurance, that is a separate document. We handle that through our jewellery appraisal service.
Use the report to judge quality. Use an appraisal to judge value. They are two different papers, and you may want both.
A few certified diamond rings from our studio
Every diamond ring below comes with an independent grading report, so you can see exactly what you are buying. Here are a few from our engagement collection.
Real pieces at Vanhess. Tap any ring for its full details.
GIA and IGI: the two labs you will see most
Two names come up again and again on diamond reports: GIA and IGI (the International Gemological Institute). Both are independent labs, both grade natural and lab-grown diamonds, and both issue reports that describe the 4Cs.
They are not identical in how buyers view them. GIA is generally seen as the strictest grader for natural diamonds, which is why a GIA report on a mined diamond often carries the most weight at resale. IGI grades the large majority of lab-grown diamonds sold today, so most lab-grown stones you look at will come with an IGI report. Neither is "fake." What matters is that the report comes from a respected, independent lab, and that the stone in front of you matches it.
| Point | GIA | IGI |
|---|---|---|
| Best known for | Natural diamonds | Lab-grown diamonds |
| Created the 4Cs | Yes | No |
| Grades lab-grown? | Yes | Yes |
| Seen as strictest for natural | Usually yes | Varies stone to stone |
| Report number on the stone | Often laser-inscribed | Often laser-inscribed |
What is on a report
Most full reports show the same core information:
- The 4Cs: cut, colour, clarity, and carat weight.
- Measurements and proportions: the exact size and angles of the stone.
- Polish and symmetry: how well the diamond was finished.
- Fluorescence: whether the stone glows under ultraviolet light.
- A clarity plot: a small map showing where any inclusions sit.
- A report number: often laser-inscribed on the girdle (the thin edge of the diamond) so you can match the stone to its paper.
It helps to know what a diamond is in the first place. Under the US FTC Jewelry Guides, a diamond is defined as "a mineral consisting essentially of pure carbon crystallized in the isometric system," with a hardness of 10. That definition covers both mined and lab-grown diamonds, because they share the same makeup.
How to check a report is real
- Find the report number on the document.
- Match it to the laser inscription on the girdle. A jeweller can show you this under magnification.
- Type the number into the grading lab's own online report-check tool and confirm the details match.
If the numbers do not match, or the stone has no matching report, ask questions before you buy. When you look at cut, colour, and clarity, start with cut, because it drives most of the sparkle. Our diamond buying guide and diamond shapes guide walk through how these choices change the look of a ring.
Lab-grown diamonds and honest labelling
Lab-grown diamonds have the same makeup and the same hardness as mined diamonds. The important thing is clear labelling. The FTC Jewelry Guides say a seller must clearly tell you when a stone is not mined, using a word such as "laboratory-grown," "laboratory-created," or "[maker]-created."
Be careful with the word "real." A lab-grown diamond is a real diamond, but it must still be labelled as lab-grown. If a seller is vague about whether a stone is mined or grown, slow down and ask.
If you are weighing one against the other, read our lab-grown vs natural diamond guide. If you are open to other stones, our moissanite guide covers a popular alternative.
Certified diamond styles at Vanhess
We design and make most of what we sell, on site in Coquitlam. Each of these rings is set with a graded diamond, and we will walk you through the report in person.
A sample of our engagement rings. Prices are a starting point and vary by diamond.
Why this matters when you buy
Buy the stone, not the paper. A report is a tool to compare stones fairly and to protect you, not the thing you are buying. But a report from a respected, independent lab tells you the quality is described by someone with no stake in the sale. For a ring you will wear every day for decades, that is worth having. Our full engagement ring guide puts all of this together.
Frequently Asked Questions
Is a diamond grading report the same as an appraisal?
No, they are two different documents with different jobs. A grading report describes a diamond's quality, recording the 4Cs and the stone's measurements against fixed standards so you can compare diamonds fairly. It deliberately does not state a price. An appraisal, on the other hand, assigns a monetary value, usually so you can insure the piece for the right amount. You often want both: the report to help you choose the stone, and the appraisal to protect it once it is yours. Confusing the two is a common and expensive mistake, because a report says nothing about value and an appraisal is not an independent quality assessment. We prepare appraisals in our Coquitlam studio and are happy to explain how each document is used.
Which is better, GIA or IGI?
Both are respected independent laboratories, so neither is a poor choice, but they have different reputations. GIA created the modern grading system and is generally regarded as the strictest grader of natural diamonds, which is why a GIA report on a mined stone often carries the most weight when you resell. IGI grades the large majority of lab-grown diamonds sold today and is widely accepted for them, so most lab-grown stones you look at will come with an IGI report. For a mined diamond many buyers prefer GIA, while for a lab-grown diamond an IGI report is completely normal. What matters most is that the report comes from a recognised, independent lab and that the stone in front of you actually matches it, which we will always check with you.
Do lab-grown diamonds come with reports?
Yes, lab-grown diamonds are graded and reported much like mined ones, most often by IGI. The report covers the same 4Cs, measurements and proportions, and it should state clearly that the stone is laboratory-grown, since honest labelling is required by law. Many lab-grown diamonds are also laser-inscribed on the girdle with a report number and a note that they are lab-created, so you can match the paper to the exact stone under magnification. This means you get the same reassurance about quality that you would with a mined diamond, plus a clear record of origin. If a lab-grown diamond is being sold without any report, or without a clear statement that it is lab-grown, treat that as a reason to slow down and ask questions before you buy.
Can I check a diamond report online?
Yes, the major grading labs keep free online report-check tools, and using one is a smart habit. Find the report number on the document, enter it on the lab's own website, and confirm that the details shown, the 4Cs, measurements and any comments, match the paper you are holding. If the diamond is laser-inscribed, you can also match that number on the girdle under magnification to be sure the report belongs to that exact stone and was not swapped in from a better diamond. A report that cannot be found in the lab's database, or details that do not match, is a clear warning sign. If you are unsure how to do this, bring the stone and its report to our studio and we will check it online and under the loupe together.
Does Vanhess grade or certify diamonds?
No, and that is by design. Grading is done by independent laboratories such as GIA and IGI, not by the shop selling the stone, because independence is the whole point of a report. What we do is help you use it. At our Coquitlam studio we will read any grading report with you line by line, match the laser inscription on the girdle to the report number so you know the paper belongs to that diamond, and explain what each grade means for how the stone actually looks. We also prepare separate appraisals that assign an insurance value, which is a different document from a grading report. So we are your guide to the paperwork and your goldsmith, while the grading itself stays in independent hands.