How to Read an IGI Lab Grown Diamond Report: Line-by-Line Guide

An IGI report for a lab grown diamond tells you exactly what you are buying: the stone's shape, measurements, carat weight, color, clarity, finish and how it was grown. Once you know where each grade sits on the page and which lines matter most, you can compare two "1 carat lab diamonds" in minutes and spot the one that is truly the better value.

What an IGI lab grown diamond report is

The International Gemological Institute (IGI) is one of the most widely used independent labs for grading laboratory-grown diamonds. Its report is a written assessment of one specific stone. It does not set a price, and it is not an appraisal for insurance. Instead, it documents the stone's characteristics so you can compare diamonds on equal terms.

IGI grades lab grown diamonds on the same scales used for natural diamonds: D to Z for color and FL to I3 for clarity. That means a G VS2 lab diamond is graded by the same standard as a G VS2 mined diamond, which makes side-by-side shopping much easier. If you are still deciding between the two origins, our guide on why IGI certification matters covers the bigger picture.

How to read an IGI report, line by line

Layouts vary slightly by report type, but you will find these fields on most IGI lab grown diamond reports.

1. Report number and date. A unique number that ties the paper to one stone. You will use it to verify the report online.
2. Description. It should clearly say "Laboratory-Grown Diamond." If it does not, ask why.
3. Shape and cutting style. For example, "Oval Brilliant" or "Emerald Step Cut."
4. Measurements. Length x width x depth in millimeters. For fancy shapes, divide length by width to get the length-to-width ratio, which controls how slim or chunky the stone looks.
5. Carat weight. Weight, not size. Two stones of the same weight can face up differently depending on cut and depth.
6. Color grade. D, E and F are colorless; G through J are near colorless and look white face-up to most people, especially in yellow or rose gold.
7. Clarity grade. FL and IF are flawless; VVS and VS stones have inclusions you are unlikely to see without magnification; SI stones can be eye-clean or not, so ask for photos or video.
8. Cut grade. Usually given for round brilliants. Fancy shapes such as ovals, pears and emeralds typically do not receive an overall cut grade, so polish, symmetry and proportions matter more.
9. Polish and symmetry. Grades for the quality of the finish. Excellent or Very Good is what most buyers look for.
10. Fluorescence. How the stone reacts to UV light. "None" or "Faint" is common and rarely a concern.
11. Comments. Often the most overlooked section. Look here for the growth method and any treatment note.
12. Inscription. Many IGI-graded lab diamonds carry a microscopic laser inscription of the report number on the girdle, which links the stone to its paperwork.

Understanding the growth method and treatment note

Lab grown diamonds are produced by one of two methods, and IGI reports usually state which one in the comments:

• CVD (chemical vapor deposition): carbon is deposited layer by layer onto a diamond seed.
• HPHT (high pressure, high temperature): conditions similar to those deep in the earth are recreated to crystallize carbon.

Both produce real diamond with the same chemistry and hardness. Neither method is automatically better; judge the finished stone by its grades and how it looks.

You may also see a note about post-growth treatment, or a statement such as "As Grown," meaning no indication of post-growth treatment was found. Many CVD diamonds receive a post-growth treatment to improve color. It is a recognized, permanent process, but it is worth knowing so you are comparing like with like.

How to verify an IGI report online

1. Find the report number on the paper or digital certificate.
2. Enter it in the report verification tool on IGI's official website.
3. Check that the shape, measurements, carat weight, color and clarity match what the seller listed.
4. If the stone is inscribed, a jeweler's loupe or microscope can confirm the number on the girdle matches the report.

If any detail does not match, pause and ask questions before you buy.

Which grades give the best value?

There is no single "right" grade, but these ranges work well for many US shoppers buying an engagement ring:

• Color: E to G for an icy look in platinum or white gold; G to H is often plenty in yellow or rose gold.
• Clarity: VS1 to VS2 is a sweet spot because inclusions are usually invisible to the eye.
• Finish: Excellent or Very Good polish and symmetry.
• Proportions: For fancy shapes, a pleasing length-to-width ratio and a depth that does not hide weight underneath the stone.

Lab grown diamonds let you put more of your budget toward size. If you are weighing a bigger stone, see our comparison of 1 carat vs 2 carat engagement rings. And if long-term value is on your mind, read whether lab grown diamonds have resale value before you decide.

Red flags to watch for

• A report that does not clearly identify the stone as laboratory-grown.
• Grades listed by a seller with no report number you can check.
• Measurements that do not match the stone you are shown.
• An SI clarity stone sold with no photos or video to confirm it is eye-clean.

At Claire Diamonds, every ring is handcrafted to order, and you can ask us about IGI certification for your center stone before you buy. Browse our lab grown diamond engagement rings, from classic lab grown solitaire rings to modern bezel set lab grown rings.

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Every order ships free with insured US shipping and is backed by our 30-day returns.

Frequently asked questions

Is an IGI report the same as a certificate?

Yes, in everyday shopping language. "IGI certificate" and "IGI report" usually refer to the same grading document; technically, IGI issues a grading report describing the stone.

Does every lab grown diamond come with an IGI report?

Not always. Grading reports are common for center stones, while small accent diamonds are usually not graded individually. If a report matters to you, ask before you order.

Does an IGI report tell me what a diamond is worth?

No. A grading report describes quality, not price. For insurance, you would ask for a separate appraisal.

Can I tell a lab grown diamond from a natural one without a report?

Not by eye. Lab grown and natural diamonds look the same, which is why a lab report and laser inscription are so useful for confirming origin.

Ready to choose your stone? Explore our lab grown diamond engagement rings and ask us about IGI certification for your center stone.