Two names. One question that comes up in almost every lab-grown diamond conversation. And an answer that has changed significantly since late 2025.
If you have been researching lab-grown diamonds, you have almost certainly come across both IGI and GIA. You may have noticed that some stones carry one certificate and some the other, and that the price difference between them is not always obvious. What is less widely known is that GIA fundamentally changed how it grades lab-grown diamonds in October 2025 - a shift that makes the comparison between the two institutions more nuanced, and more important to understand, than it has ever been.
This guide explains what each certificate actually represents, what changed, and what it means when you are choosing a lab-grown diamond for your engagement ring.
What Is a Diamond Certificate?
A diamond certificate (sometimes called a grading report) is an independent document issued by a gemological laboratory after a stone has been examined by trained graders. It records the diamond's cut, colour, clarity, and carat weight, along with additional details such as fluorescence, polish, symmetry, and proportions.
For a lab-grown diamond, the certificate will also typically note the method used to grow the stone: either CVD (Chemical Vapour Deposition) or HPHT (High Pressure High Temperature).
A certificate is not a valuation or an insurance document. It is a quality record: independent, third-party verification of exactly what the stone is and how it grades. For a purchase made online, that independent verification is one of the most important assurances a buyer has.
Not every lab-grown diamond on the market comes with a certificate, and not every certificate carries equal weight. Understanding which lab issued your stone's report, and what that means in practice, is worth knowing before you commit. To understand what the individual grades on a certificate actually mean, the complete 4Cs guide is a useful companion to this one.
Who Are IGI and GIA?
GIA — the Gemological Institute of America was founded in 1931 and created the 4Cs grading system that the entire industry now uses. For decades it was considered the definitive standard in diamond grading globally, particularly for natural diamonds, and its name carries genuine weight in the trade. GIA began certifying lab-grown diamonds in 2007.
IGI — the International Gemological Institute was founded in Antwerp in 1975 and has grown into the world's largest independent gem certification body by volume, holding approximately 65% of the global lab-grown diamond certification market. IGI began grading lab-grown diamonds before GIA and has invested heavily in building out its lab-grown infrastructure as the market has grown. It is the dominant certification in the lab-grown diamond industry globally, and the name most buyers, jewellers, and retailers encounter when sourcing lab-grown stones.
What GIA Changed in October 2025 — and Why It Matters
In October 2025, GIA made a significant change to how it grades lab-grown diamonds. Rather than issuing individual 4Cs grade reports, assigning specific colour, clarity, and cut grades to each stone - GIA now assigns lab-grown diamonds a simplified descriptor: either Premium or Standard.
Under GIA's new system, a Premium classification requires D colour, VVS or better clarity, and Excellent cut, polish, and symmetry for round brilliants. Standard covers a broader range: VS clarity, E to J colour, and Very Good grades across cut, polish, and symmetry. Stones that do not meet the Standard threshold receive no quality classification at all.
GIA's stated rationale was that more than 95% of lab-grown diamonds entering the market fall into a very narrow range of colour and clarity, making the full continuum of natural diamond grading less relevant to apply. From a scientific perspective, that argument has merit. From a buyer's perspective, the practical implication is significant: a GIA report on a lab-grown diamond no longer tells you the stone's individual colour grade, its specific clarity grade, or its cut grade. It tells you the stone cleared a threshold.
IGI continues to issue full 4Cs grading reports for lab-grown diamonds, assigning individual grades for cut, colour, clarity, and carat weight on every stone. That level of detail and the ability to know precisely that a stone is, for example, E colour, VVS1 clarity, Excellent cut - remains available through IGI but no longer through GIA for lab-grown diamonds.
What About Other Certificates?
IGI and GIA are not the only gemological laboratories issuing certificates for lab-grown diamonds. Other laboratories include GCAL, EGL, and a number of smaller regional labs, all produce grading reports that you may encounter when shopping.
These certificates are not equivalent. The grading standards, consistency, and international recognition of lesser-known labs vary considerably, and some have been found to apply more lenient grading criteria than IGI or GIA. A stone that receives a VS1 clarity grade from one of these labs may not meet the same standard that grade implies under a more rigorous evaluation. For a purchase as significant as an engagement ring, this matters: a more generously graded stone is not necessarily a better stone, and the grade on the certificate should reflect reality rather than optimism.
The Jewel Concierge sources exclusively IGI and GIA certified diamonds - the two institutions with the deepest grading rigour, the most consistent standards, and the widest international recognition in the industry.
The Price Difference Between IGI and GIA Certified Stones
In the current market, GIA certified lab-grown diamonds typically carry a modest price premium over equivalent IGI certified stones - broadly in the range of 10 to 15%. This reflects GIA's longer-established global reputation rather than any meaningful difference in the quality of the stone itself.
Given GIA's October 2025 change to its lab-grown grading system, this premium is worth considering carefully. An IGI certificate provides individual 4Cs grades; specific, independently verified quality data for the stone you are buying. A GIA assessment now provides a category label. For many buyers, the additional transparency of a full IGI report represents better value than a GIA Premium descriptor at a higher price point, particularly when both stones are held to the same internal quality standards before being offered for sale.
What The Jewel Concierge Offers - and Why the Standards Matter More Than the Label
At The Jewel Concierge, we offer clients the option to choose from both IGI and GIA certified diamonds, whether you are designing your piece using our ring builder, or through our custom ring design process. You are not limited to one certification, and the choice between them does not affect the quality of the stone, because The Jewel Concierge's sourcing standards are applied before the certificate becomes relevant.
Every lab-grown diamond you will see is D-F colour, VS2-VVS1+ clarity, and carries excellent cut, polish, and symmetry grades. Every stone is also 100% carbon-neutral. These are not aspirational ranges; they are the minimum standards applied to every stone sourced, regardless of which laboratory graded it.
In practical terms, this means a buyer choosing between an IGI and GIA certified stone from The Jewel Concierge is not choosing between different quality levels. They are choosing between two credible certifications, both of which confirm the same underlying quality. The IGI certificate will provide more granular grading detail. The GIA assessment will confirm the stone meets its Premium threshold. Both are legitimate. The most useful thing to focus on is the specific stone, the shape, and the size, and one of our expertrs can walk you through what is available across both certifications within your preferences.
Browse the full lab-grown diamond engagement ring collection to explore the range, or read more about how lab-grown diamonds are created and graded in the complete lab-grown diamond guide. More detail on The Jewel Concierge's sourcing standards is available on our lab-grown diamonds page.
Frequently Asked Questions
What is the difference between IGI and GIA for lab-grown diamonds?
IGI issues full 4Cs grading reports for lab-grown diamonds, assigning individual grades for cut, colour, clarity, and carat weight. Since October 2025, GIA no longer issues 4Cs reports for lab-grown stones; it now assigns a simplified Premium or Standard label based on an overall quality assessment. For buyers who want complete grading detail, IGI is the more informative option for lab-grown diamonds specifically.
Is IGI or GIA better for lab-grown diamonds?
For lab-grown diamonds, IGI is the industry-leading certification. It holds approximately 65% of the global lab-grown certification market, issues detailed 4Cs grading reports, and has the deepest specialisation in lab-grown stones. GIA is the older and more widely known institution, but its October 2025 move to simplified Premium/Standard labels for lab-grown diamonds means it no longer provides the same level of grading detail that IGI does.
What happened to GIA lab-grown diamond grading in 2025?
In October 2025, GIA replaced its traditional 4Cs grading reports for lab-grown diamonds with a simplified two-tier system. Lab-grown diamonds now receive either a Premium label (requiring D colour, VVS or better clarity, and Excellent grades across cut, polish, and symmetry) or a Standard label (covering a broader quality range). Individual cut, colour, and clarity grades are no longer reported on GIA lab-grown diamond certificates.
Should I avoid other diamond certificates?
IGI and GIA are the two most trusted and widely recognised certification bodies in the fine jewellery industry. Lesser-known labs, including GCAL, EGL, and others, carry less industry recognition and have in some cases been found to apply more lenient grading standards, which can result in a stone receiving a higher grade than it would earn under a more rigorous evaluation. For a purchase as significant as an engagement ring, sticking to IGI or GIA provides the most reliable assurance of what you are actually getting.
What quality standards does The Jewel Concierge apply to its lab-grown diamonds?
Every lab-grown diamond at The Jewel Concierge is D-F colour, VS2-VVS1+ clarity, with excellent cut, polish, and symmetry. All stones are 100% carbon-neutral and certified by either IGI or GIA. These standards are applied consistently to every stone in the collection, regardless of which certification it carries.
Can I choose between an IGI and GIA certified diamond at The Jewel Concierge?
Yes. Both IGI and GIA certified diamonds are available through The Jewel Concierge's ring builder and through the Bespoke Journey. A consultant can walk you through the specific options available within your preferred shape, size, and budget.
The Certificate Is the Starting Point, Not the Whole Story
A diamond certificate tells you what a stone is. What it cannot tell you is whether the jeweller sourced it thoughtfully, whether the setting it sits in is well made, or whether you are receiving honest guidance through the process of choosing it.
At The Jewel Concierge, the certificate is the foundation - independent verification that every stone meets the quality parameters set before it enters the collection. What sits on top of that foundation is considered craftsmanship, genuine expertise, and a buying experience built around guidance rather than pressure.
If you have questions about certification, quality grades, or what to look for when choosing a lab-grown diamond, book your complimentary virtual consultation and be guided by one of our experts.
