If you are comparing IGI vs GIA for a lab-grown diamond, the key difference is no longer simply which laboratory has the stronger reputation. The two organisations now approach laboratory-grown diamond reporting differently, so buyers need to understand what information each report actually provides.
Both the International Gemological Institute (IGI) and Gemological Institute of America (GIA) offer independent diamond evaluations. Even though a grading document may help you identify the origin and describe the quality attributes, it cannot indicate if a particular diamond is good value, eye-pleasing or has a potential to hold a certain resale price.
To Australian buyers searching for an engagement ring or loose lab grown diamonds, the report should be just one criterion in the overall quality assessment.
What Does IGI Report on a Lab-Grown Diamond?
IGI provides comprehensive information on laboratory-grown diamonds using familiar diamond quality terminology.
I GI’s reports may indicate the shape and style of a diamond’s cut, its measurements, carat weight, colour, clarity, information on its cut (where relevant), plus polish and symmetry. IGI also indicates if a diamond is laboratory grown, as opposed to being mined.
The colour of colourless diamonds is graded using the familiar D-to-Z scale, while the clarity can range from IF, VVS, VS, SI to Included. The assessment looks at characteristics seen when magnified and considers their size, number, position and type.
This comprehensive approach to diamond grading is particularly helpful if you want to compare two loose lab-grown diamonds specification by specification.
For example, a buyer could compare an IGI-graded 1.5-carat oval with another stone of the same carat weight checking out the differences in colour, clarity, dimensions, polish and symmetry rather than assuming they are equivalent just because their carat weights are the same.
How Does GIA Assess Lab-Grown Diamonds Now?
GIA has revised its grading practices for colorless-to-near-colorless laboratory-grown diamonds as of October 2025.
Rather than using the same color and clarity grading scales as with natural diamond, qualifying laboratory-grown diamonds will be graded Premium or Standard.
Diamonds graded Premium meet the higher end of the GIA grading scales for the appropriate quality factors.
Standard indicates a laboratory-grown diamond that meets the minimum requirements established by GIA, while those that do not qualify for a Standard grade would not have the same quality designation.
A GIA laboratory-grown designation includes identifying the stone as laboratory-grown and laser-engraving the girdle with the laboratory identification and grading number.
Therefore, a current GIA laboratory-grown grading report should not be confused with a traditional GIA natural diamond grading report.
IGI and GIA Compared
| Factor | IGI | GIA |
|---|---|---|
| Confirms laboratory-grown origin | Yes | Yes |
| Detailed colour grades | Uses D-to-Z terminology | Current qualifying stones use Premium/Standard assessment |
| Detailed clarity grades | Uses familiar clarity grades | Included within overall quality assessment criteria |
| Carat and measurements | Reported | Assessed as part of laboratory service |
| Polish and symmetry | Reported | Used in quality assessment |
| Report verification | Available | Available |
| Useful for specification-by-specification shopping | Particularly useful | More focused on overall quality classification |
The difference matters because two reports may communicate diamond quality in different ways even though both come from established gemmological laboratories.
Does One Laboratory Make a Diamond Better?
No. The laboratory cannot improve the stone. The appearance of the diamond depends only on the characteristics of the diamond itself, such as cut, proportionality, color, clarity, carat and shape. This is stated in the laboratory report — the description or assessment of these characteristics according to the rating system established by the laboratory.
A properly cut laboratory diamond with good proportions will not become more dazzling because of the name on the certificate.
A stone with an extremely high clarity rating will not look better because of it. If the inclusions are not visible to the naked eye, then it makes no sense to waste money on the cut or on the shape and size of the diamond.
Why the Report Still Matters When Buying
A grading report gives you an independent reference point for comparing what a retailer says about a diamond with what a gemmological laboratory has assessed.
Buyers researching igi vs gia through Australian lab-grown diamond retailers such as novitadiamonds.com should still examine the individual stone rather than choosing solely according to the laboratory name.
Before purchasing, check:
- whether the report clearly identifies the diamond as laboratory grown
- whether the report number can be verified with the issuing laboratory
- whether measurements match the stone being offered
- whether the grading document corresponds to the diamond’s laser inscription where applicable
- whether carat weight refers to the centre stone or total jewellery carat weight
- the retailer’s return, resizing and after-sales terms
A grading report is also lab created diamonds from an appraisal. It describes or evaluates gemmological characteristics; it does not guarantee retail price, future resale value or investment performance.
Compare the Diamond, Not Just the Certificate
For engagement-ring buyers, there are qualities that affect what you will see.
You need to think about the cut and proportions as they can strongly affect light performance. You might not notice the difference in face-up size between two diamonds of equal carat weight. Remember, too, that shape affects visual spread: an oval, emerald, radiant and round diamond of equal weight will not look the same on the finger.
You should also consider the colour in the context of the setting. The visible effect of a particular grade may vary depending on diamond shape and whether you choose platinum, white gold, yellow gold or rose gold.
Finally, you should think about clarity. Rather than paying for higher grades automatically, ask yourself whether individual inclusions are visible to the naked eye, and whether they have an impact on the appearance or durability.
Which Report Should Australian Buyers Prefer?
There is no simple answer. IGI’s detailed grading format could be useful for buyers seeking to compare individual lab-created diamonds using specific color, clarity and other 4Cs information. GIA’s current system takes a broader approach by classifying qualifying colorless-to-near-colorless lab-created diamonds as Premium or Standard.
The reality is that you have to be able to understand the report in front of you, rather than assume that the name of the laboratory alone resolves the transaction.
Do your due diligence on the document, compare the stone’s measurements and quality characteristics, inspect images or the diamond itself where possible, and compare like with like. Doing this gives you far more information that is useful to you than just treating either grading laboratory as a substitute for inspection of the diamond itself.