If you are comparing diamonds online, you will quickly see two certification names again and again: IGI and GIA.

Both are independent gem laboratories that grade diamonds. A certificate does not make a diamond better, but it helps you understand what you are buying and compare stones more fairly.

This guide explains the practical differences between IGI and GIA, and what matters most for buyers in the EU.

What is a diamond certificate?

A diamond certificate is a grading report issued by an independent lab. It describes the diamond’s key characteristics, including cut, color, clarity, and carat weight. It can also include proportions, measurements, fluorescence, and a plotting diagram for many natural diamonds.

Certificates are used to reduce guesswork and make comparisons easier when you are not viewing a diamond in person.

What is GIA?

Gemological Institute of America (GIA) was founded in 1931 in the United States by gemologist Robert M. Shipley.

GIA was created to bring scientific standards, education, and consistency to the gemstone and jewelry industry at a time when grading practices varied widely.

GIA is best known for developing and formalizing the 4Cs grading system: cut, color, clarity, and carat weight. This framework is now the global standard used to describe and compare diamonds.

Today, GIA operates as a non profit organization and is widely regarded as one of the strictest and most consistent grading authorities, particularly for natural diamonds. Its reports are commonly used for higher value stones and are recognized worldwide.

Many buyers choose GIA certified diamonds because of the institute’s long history, conservative grading approach, and strong international reputation.

What is IGI? 

International Gemological Institute (IGI) was founded in 1975 in Antwerp, Belgium, one of the world’s historic diamond trading centers.

IGI operates laboratories and educational institutes across Europe, Asia, and North America. It issues grading reports for both natural and lab grown diamonds and is one of the most widely used gem laboratories globally.

IGI is especially prominent in the lab grown diamond market, where it provides certification at scale for modern diamond production. In the EU market, IGI certified lab grown diamonds are extremely common and widely accepted.

While grading philosophies can differ slightly between laboratories, IGI reports provide detailed information on a diamond’s characteristics and are used by many established suppliers and retailers worldwide.

IGI vs GIA: the key differences

Here are the differences that matter in real life.

1) Consistency and strictness

GIA is often described as stricter, particularly for color and clarity.

IGI is generally reliable, but some buyers and professionals consider it slightly more lenient on average.

What this means for you: if two diamonds have the same grades, the one graded by a stricter lab may be a safer bet. The only way to be sure is to review the certificate details and the actual diamond visuals.

2) Lab grown diamonds

IGI is the most common certificate for lab grown diamonds.

GIA also grades lab grown diamonds, but availability depends on supplier and region.

What this means for you: if you are shopping lab grown, you will see a lot of IGI. That is normal.

3) Natural diamonds

GIA is extremely common for natural diamonds, especially in higher value stones.

IGI is also used for natural diamonds, but it is less dominant in the premium segment.

What this means for you: if you are shopping natural, you will often see GIA, especially as price increases.

What matters more than the lab name

For most buyers, these factors matter more than whether the report says IGI or GIA.

• Cut quality and proportions
• Light performance in video, not just grades
• The full set of measurements, not only the headline grades
• Matching your priorities, for example size, brightness, or minimal inclusions

A certificate is a tool. The diamond itself is the product.

Can a certificate guarantee the diamond is conflict free?

A certificate is a grading report, not a legal compliance document.

If conflict free sourcing and compliance matter to you, look for clear seller policies, transparent supply chain practices, and region specific compliance statements.

How Carateu uses diamond certificates

Carateu lists diamonds that are independently certified by IGI or GIA. Each diamond is reviewed before shipping to customers within the EU.

For additional transparency, diamonds on Carateu are reviewed by a gemologist trained by both institutions. Our in-house expertise includes Graduate Gemmologist training from IGI and Jewelry Essentials certification from GIA.

Our aim is to make it easier to compare certified diamonds using clear information, straightforward pricing, and EU-focused fulfillment.

FAQ

Is IGI a real diamond certificate?
Yes. IGI is an independent gem lab and its reports are widely used for both natural and lab grown diamonds.

Is GIA better than IGI?
Many professionals consider GIA stricter, especially for natural diamonds. In practice, what matters most is the diamond’s cut quality, proportions, and how it looks in video.

Is IGI OK for lab grown diamonds?
Yes. IGI is the most common certification for lab grown diamonds and is widely accepted in the EU market.

Should I only buy GIA certified diamonds?
Not necessarily. Many excellent diamonds are IGI certified. Use the certificate as a tool and compare the full report details and visuals.

If you would like help reading a certificate, contact us and we will guide you through what to look for.