GIA vs IGI: choosing a diamond with confidence

What is the difference between GIA and IGI?

GIA stands for Gemological Institute of America; IGI stands for International Gemological Institute. Both examine natural and laboratory-grown diamonds.

For natural diamonds, compare the actual grades, the stone’s appearance and the price. Ask your jeweller to explain any differences between reports.

Scroll the table to compare both laboratories.

See the laboratories' own descriptions of GIA natural-diamond reports, GIA lab-grown services, IGI diamond reports and IGI cut assessment.

Is IGI a good choice for a lab-grown diamond?

Yes. IGI's lab-grown reports give you practical details to compare: the diamond's identity, shape, measurements, carat weight, colour and clarity, along with relevant cut information. Having individual grades is useful when you are narrowing a shortlist. IGI's report guide explains these fields.

Use those grades to shortlist, then compare the actual stones. The same care applies to a diamond with a GIA report.

Read the comments as well as the headline grades. IGI says details of how a diamond was grown and any treatments can be included upon request. Ask your jeweller to check what information is available. IGI lab-grown reporting

What changed in GIA's lab-grown reports?

Since 1 October 2025, GIA’s colourless-to-near-colourless lab-grown service has used overall Premium or Standard assessments. IGI reports give individual quality grades. A GIA category cannot be translated into one exact IGI colour and clarity grade.

Older GIA lab-grown reports remain valid. Check the document's date and service type before assuming what it should contain. GIA's confirmation

How to compare two diamonds fairly

Start with the same diamond type: natural against natural, or lab-grown against lab-grown. Then compare similar shapes and weights, and work through these points:

1. Read the actual reports. A search listing summarises selected fields. The report gives you the laboratory's wording, measurements and any relevant comments.
2. Check the grading system. Reports from the same laboratory and service can be easier to compare. Across laboratories, ask about the format and criteria; do not assume a fixed grade adjustment. Even matching grades do not make two stones identical.
3. Consider the shape and proportions. Measurements help explain the size you will see when looking down at the ring. Cut reporting also varies: A standard GIA report does not provide the same overall cut grade for an oval as it does for a standard round brilliant. Polish and symmetry are separate assessments. GIA on fancy-shape cut grading
4. Look at the diamond in motion. Review a clear video or inspect the stone in different lighting, looking at brightness, transparency and the pattern of light and dark areas. For elongated shapes, discuss any prominent bow-tie shadow across the centre. A still photograph cannot show every viewing angle. GIA's oval-diamond guide explains why viewing the stone matters.

A report is valuable evidence, but it cannot decide which outline, proportions or sparkle you enjoy most. Bring your shortlist into the design conversation so the diamond and setting can be considered together.

What do GIA and IGI reports look like?

Often called diamond certificates, these reports record the laboratory's findings. The photos below show a GIA natural-diamond report and an IGI jewellery-report example. They cover different report types and are not a direct comparison of grades.

GIA natural-diamond report

IGI jewellery-report example

When checking your own report, start with the diamond's identity, report number, measurements and grading details, then read the comments. GIA's current colourless-to-near-colourless lab-grown assessment has a different layout from the natural-diamond example above.

Where is the report number on the diamond?

A report number may be laser-inscribed on a diamond’s girdle, the narrow edge around its widest part. A jeweller can read it under magnification and compare it with the report. Both GIA and IGI offer this service. IGI explains its Laserscribe service.

Inscription is included with some report services and optional with others, so check the individual report. GIA's current colourless-to-near-colourless lab-grown service inscribes “Laboratory-Grown” and the quality assessment number. GIA natural-diamond services and lab-grown services explain the difference.

How to check a GIA or IGI report

Check the record, then match it to the diamond.

1. Enter the report number through GIA Report Check or IGI Verify Your Report.
2. Compare the returned details with the document supplied, including the stone's natural or laboratory-grown description, measurements and grading information.
3. Ask your jeweller to match the stone to the report. Where a laser inscription is present, compare it under suitable magnification alongside other identifying features.

Finding a genuine report online confirms that the laboratory has that record. It does not, by itself, authenticate the diamond in front of you. An inscription is another useful check, rather than the entire identification process. GIA's identification case notes illustrate why matching matters.

Compare current prices alongside the reports

Use Anny's current natural-diamond listings or lab-grown diamond listings to compare available stones. Keep the diamond type, shape, weight and quality details in view when assessing a price difference.

A loose-diamond price is for the stone; the setting, metal and making of your ring need a separate quote. Ask us about availability and viewing arrangements for a shortlisted diamond. An online listing does not mean the stone is physically in either showroom.

A few common questions