The short answer: IGI and GIA are both well known gemmological laboratories that grade diamonds, including lab grown ones, and both give you an independent report. The reports look and read a little differently, so the useful step is to compare the stone itself and check that each report can be verified.
When you shop for a lab grown diamond you will often see a report from one of these two labs. Understanding what each report gives you helps you compare stones fairly, though a report is only part of the picture.
What both labs provide
- An independent description of the diamond, including shape, measurements and carat weight.
- Colour and clarity grades.
- An origin statement that says the stone is laboratory grown.
- A report number you can check on the lab's website.
Where the reports differ
| IGI | GIA | |
|---|---|---|
| Reputation | Widely used for lab grown stones | Widely known for grading natural diamonds as well |
| Report style | Full reports and shorter formats | Reports and digital formats for lab grown stones |
| What it covers | Grades plus growth and treatment details | Grades plus growth and treatment details |
Both are respected, and layouts and detail change over time, so read the individual report rather than relying on a lab name alone.
Why two stones with the same grades can look different
A report gives grades, but two stones with the same grades can look different in person. Cut quality, how the light moves and personal taste all matter. That is why we show you stones on video, in different lighting, as well as going through the report with you.
Grading scales
Most labs describe diamonds with colour grades from D, which is the whitest, down through the alphabet, and clarity grades from flawless to included. Cut grades describe how well the proportions return light. The scales are similar between labs, but labs apply them with their own judgement, so a stone graded one step higher at one lab may look the same as a stone graded one step lower at another. The scales are a guide, not a promise of identical appearance.
Reading the extra details
Beyond the main grades, a report may list polish, symmetry, fluorescence, proportions and comments. For a lab grown stone, the comments often mention the growth method and any treatment after growth. These details help explain why a stone looks the way it does, so it is worth reading the whole report, not just the headline grades. See HPHT and CVD lab grown diamonds.
How to use a report
- Check the report number on the lab's website.
- Confirm the origin, shape, weight and grades match the listing.
- Ask us if any wording is unclear.
Do not choose on the lab alone
It is more helpful to compare stones on their individual quality than to assume that one lab is better in every case. A well cut stone with a good report from either lab is a sound choice, and we can explain what each line means. For natural diamonds, see GIA vs IGI certification for natural diamonds.
See what a lab grown diamond report must show, and browse lab grown colourless diamonds. Nothing is made until you approve the design in writing, and our standard making time is 5 to 6 weeks, which can vary with your location and how busy we are. Pieces start from £600.
Frequently asked questions
Is IGI or GIA better? Both are respected, and the right question is whether the individual stone and report suit you.
Do you work with other labs? We can discuss any report you have, and we will tell you plainly what it shows.
Can a report be wrong? Grading involves expert judgement, so small differences between labs can occur.
Does the lab change the price? It can, so compare stones on their individual merits.
Can I order from overseas? Yes, by video consultation, with insured, tracked FedEx delivery.