To read an IGI lab-grown diamond report, start with the 4Cs: color, clarity, cut and carat weight. Then check how the stone was grown, whether it was treated after growth, the laser inscription, and the report number on IGI's website. Unlike some laboratories, IGI still gives lab-grown diamonds individual color and clarity grades on the same scale used for mined diamonds, so the report tells you exactly where your stone sits.
This guide walks through each part. If you're still choosing a stone, start with our guide on what to ask your jeweler before buying a lab-grown diamond.
At a glance
- Document: IGI Laboratory-Grown Diamond Report
- Grades: the full 4Cs, color, clarity, cut and carat weight
- Origin: growth method (CVD or HPHT) and any post-growth treatment
- Laser inscription: "LG" followed by the report number
- Verify it: IGI's online report verification
The 4Cs on an IGI report
Color
Colorless lab-grown diamonds are graded on the D to Z scale. D is completely colorless, and each step down the alphabet shows a little more warmth. Most people can't see a difference between neighboring grades once a diamond is set, so look at the stone itself as well as the letter.
Clarity
Clarity runs from Flawless (FL) through Internally Flawless (IF), VVS1 and VVS2, VS1 and VS2, SI1 and SI2, down to I1, I2 and I3. It describes how many inclusions are visible under 10x magnification, and where they sit. VS stones and above usually look clean to the eye.
Cut
For round brilliant diamonds, the report includes a cut grade, along with separate grades for polish and symmetry. Cut decides how much light a diamond returns, so it has more effect on sparkle than any other grade. Fancy shapes receive polish and symmetry grades.
Carat weight
Carat weight is measured to two decimal places. The report also lists the stone's exact measurements in millimeters, which tell you how large it will look from above.
How the diamond was grown
Every IGI lab-grown report states that the stone is laboratory-grown and names the growth method, either CVD (chemical vapor deposition) or HPHT (high pressure, high temperature). Both produce real diamonds with the same physical and optical properties as mined ones.
The report also tells you whether the stone is "as grown" or shows indications of post-growth treatment. Many lab-grown diamonds are treated after growth to improve or change their color, and that's a normal part of how they're made. What matters is that the report tells you.
Reading a report for a colored diamond
Colored lab-grown diamonds are graded on the fancy color scale instead of D to Z. The report describes the hue, such as pink, blue, green or yellow, and its intensity, from Fancy Light through Fancy, Fancy Intense and Fancy Vivid to Fancy Deep. It also covers clarity and carat weight, and notes whether the color was produced during growth or by treatment afterwards.
A colored report is easiest to understand with the stone in front of you. See how pink Muse, blue Heavenlee, green Everly and yellow Aurelia look in the Signature Halo Collection.
The proportions diagram
Most IGI reports include a diagram of the stone's proportions, showing measurements such as table size, depth and crown and pavilion angles. Many also include a plot of the stone's inclusions. Together they work like a fingerprint and help you match the report to your exact stone.
The laser inscription
IGI laser inscribes the lab-grown diamonds it grades on the girdle, the thin outer edge, with "LG" and the report number. The inscription is invisible to the eye but readable under a 10x loupe. It's the link between the report and the stone, so always check that the numbers match.
How to verify your IGI report in four steps
- Find the report number on your document.
- Enter it in the report verification on IGI's website.
- Compare every detail on screen with your document, line by line.
- Check the inscription under magnification and confirm it shows the same number.
If the report appears in IGI's verification, it's authentic. The inscription then confirms it belongs to the stone in front of you. You need both checks.
What an IGI report covers in finished jewelry
A grading report describes one stone. In finished jewelry, that usually means the center diamond has its own report, while very small accent stones, such as the diamonds in a halo, are not graded individually. Ask which stones in your piece are documented and which report belongs to each one.
Frequently asked questions
Does IGI grade lab-grown diamonds the same way as mined diamonds?
Yes. IGI uses the same color, clarity and cut scales for lab-grown diamonds as for mined ones, and the report clearly states that the stone is laboratory-grown.
Does IGI grade colored lab-grown diamonds?
Yes. Colored lab-grown diamonds are graded on the fancy color scale, which describes their hue and intensity, and the report notes whether the color comes from growth or from treatment.
Can I get a copy of my IGI report online?
Yes. When you look up your report number in IGI's verification, you can view the report details and download a digital copy for your records.
Is an IGI report the same as a certificate?
People often call it a certificate, but it is a grading report. It describes the stone's characteristics as IGI found them. It isn't a price or a valuation.
Understanding your report
A report tells you what a diamond is. It can't tell you what it will mean to you, the moment it marks or the years you'll wear it. That part is yours to decide, and it's easier to decide when you understand exactly what you're choosing.
Our founder, Evelina Lavrenova, holds the GIA Applied Jewelry Professional diploma, and our Signature Halo Collection most recently appeared on the Flying Solo runway during New York Fashion Week. Every diamond we set comes with an IGI report, and we're happy to go through yours with you, line by line, with the stone in front of us.
