IGI vs. GIA Diamond Certification: What the Report Tells You
When you buy a diamond engagement ring, the grading report matters almost as much as the stone itself. It's an independent record of exactly what you're buying. The two names you'll see most often are IGI and GIA. Here's what each one is and how to use the report.
What is a diamond grading report?
A grading report (often called a certificate) is issued by an independent gemological laboratory. Experts examine the diamond and record its measurements and quality, so you don't have to rely on the seller's word. A report typically includes:
- Carat weight: the stone's exact weight
- Color grade: from D (colorless) down the alphabet
- Clarity grade: from Flawless through VVS, VS and SI to I
- Cut grade (for round diamonds): how well the stone is proportioned to return light
- Measurements, proportions, polish and symmetry
- A report number, often laser-inscribed on the diamond's girdle, so the stone can be matched to its paperwork
- For lab-grown stones, a clear statement that the diamond is laboratory-grown
GIA: the Gemological Institute of America
GIA is a nonprofit founded in 1931. It created the 4Cs grading system the industry uses today and is widely regarded as the benchmark for natural, earth-mined diamonds. That's why the natural diamonds in our natural diamond engagement rings come with GIA reports.
IGI: the International Gemological Institute
IGI was founded in Antwerp in 1975 and has grading labs around the world. Today it grades more lab-grown diamonds than any other lab, and its reports are the most common standard for lab-grown stones. Our lab-grown diamond engagement rings feature IGI certified center stones.
Which is better?
Both labs use the same color, clarity and carat scales, and both are trusted, independent graders. The practical difference is specialty: GIA is the go-to for natural diamonds, and IGI is the go-to for lab-grown diamonds. What matters most is that your diamond has a report from a respected lab, and that the details on that report match the stone you receive.
How to check your report
- Find the report number on your certificate.
- Look it up on the lab's website (both IGI and GIA offer free online report verification).
- Confirm the carat weight, color, clarity and measurements match what you were sold.
- If the stone is laser-inscribed, a jeweler can show you the matching number under magnification.
What about moissanite?
Moissanite isn't a diamond, so it isn't graded by diamond labs. Our moissanite is colorless (D-F) with VVS clarity and comes with a certificate of authenticity. Learn more in our guide to moissanite vs. lab-grown diamond.
Have questions about a specific stone or report? Contact us or call 310-486-8838 (daily, 9am–7pm Pacific).