Diamond Certification Guide

Gemology laboratories such as the Gemological Institute of America (GIA) can issue a quality certificate for any diamond whose dimensions, carat weight, symmetry, color, and clarity meet the required standard. Find out why you should consider buying a diamond with a certificate below.


diamond certification

Trained professionals at diamond labs evaluate, scrutinize, and measure diamonds using tools such as a microscope and a diamond grading chart. However, while several of these lab entities exist, not all of them are trustworthy and reliable. In addition, there is no set standard in the diamond industry for the certificates issued by these entities. Thus, not all diamond certificates are created equal, and the price and value of diamonds are not always comparable across the board. If you’re looking to buy a diamond with a certificate, ensure that you get one from a highly reputable grading entity and that you review the diamond certificate closely before purchase.

While diamond certification shares similarities with diamond appraisal, they are two different things. A certificate grades diamonds according to the 4Cs (carat weight, color, clarity, and cut) and provides a “blueprint” of each stone by listing its characteristics. An appraisal, on the other hand, gives a report on a diamond’s monetary worth based on quality and current market conditions. In addition, appraisals are usually carried out for insurance purposes, whereas diamond certificates instill buyers with confidence in the quality of the diamond they purchase.

If you’re looking to buy a diamond that has been carefully examined and graded by a professional, James Allen is a reputable online jewelry store that sells certified natural diamonds. You can shop their certified diamonds here.


A diamond certificate, also known as a diamond grading report, is issued by a gemological laboratory. It is based on the findings of a professional gemologist who examines the diamond using sophisticated tools and a trained eye.

diamond certification

Some of the world’s most respected independent diamond certification labs include the Gemological Institute of America (GIA) and the American Gem Society (AGS). These labs are renowned for their rigorous standards and strict protocols, but take note that their grading standards are not all the same. Each entity grades and describes diamonds differently, and sometimes the difference can have a significant impact on the quality and price of the diamonds you buy.


A diamond certificate includes details such as the diamond’s dimensions, carat weight, color, clarity, and so on (see the diamond grading chart for more information on the 4Cs, or click here). Essentially, it describes what gemologists have noted about a diamond’s color, clarity, cut, caratage, et cetera. Then, gemologists compare these characteristics to the standards of their particular institution and grade the diamond based on this comparison.


While certified diamonds aren’t necessarily better than non-certified diamonds, they provide buyers with a level of security because they guarantee the authenticity of their purchase. Buyers can also feel reassured in the knowledge that their diamond has undergone careful scrutiny by a professional and is certified high quality.

In addition, there are some instances where buying a diamond with a certificate is recommended, especially for significant jewelry purchases like engagement rings. This way, there can be no doubt about the quality of the diamond, and buyers can be assured that they are getting what they pay for.

However, even though a diamond certification usually gives some indication of the stone’s worth, buyers still need to evaluate the price of the diamond before making the purchase. After all, the price needs to accurately reflect the beauty indicated on the certificate. So, while higher-grade diamonds are often preferred for engagement rings, buyers should be aware that diamond price does not always equal diamond quality, despite what the paperwork says.


Below you will find a list of the different types of diamond certification entities and information regarding their various certification processes.



GIA stands for the Gemological Institute of America. They are a gem lab involved in grading diamonds. The GIA has robust procedures in place to ensure a diamond’s anonymity and the objectivity of the whole grading process. The GIA doesn’t certify diamonds per se but rather grades them. A GIA diamond dossier is an unbiased assessment of diamond quality based on its characteristics. The terms “GIA certified” and “GIA diamond cert” are commonly used in the jewelry industry to refer to diamonds that have undergone the GIA’s rigorous grading process and to the reports that accompany them.


The American Gem Society (AGS) established the first diamond grading standards in 1966 – standards that continue to be used in the jewelry industry today. The AGS produces unbiased diamond grading reports through their gemological laboratories and grades both mounted and unmounted gems.

The AGS diamond certification process uses the Performance-Based Cut Grade System to evaluate the overall performance of a diamond. The system grades diamonds according to the following factors: light performance (contrast, leakage, dispersion, and brightness), proportion (girdle thickness, culet size, weight ratio, durability, and tilt), and finish (polish and symmetry). However, the AGS can only assign a diamond cut grade to loose diamonds that are round brilliant cuts, square princess cuts, emerald cuts, oval cuts, and cushion cuts.


The European Gemological Laboratory (EGL) is another gem grading organization made up of several independent gemological laboratories that were established in 1974. They issue European Gemological Laboratory diamond certifications. For the most part, an EGL-certified diamond compares equally in quality to a GIA-certified diamond graded two color grades and one clarity grade lower.


The International Gemological Institute (IGI) operates from 18 laboratories across the globe and assesses diamonds according to international diamond grading standards. Thus, an IGI diamond certification is one you can trust.

In addition to providing an accurate report of a diamond’s cut, color, clarity, and carat weight, the IGI also examines the origin of a diamond and will be able to tell if the stone was naturally mined or lab-grown.


The Independent Gemmological Laboratory (IGL) is Australia’s leading diamond certification lab and, unlike many other diamond certifiers, they are not affiliated with any diamond manufacturers.

To maintain the quality of their work, IGL uses a strict vetting process to ensure that the IGL diamond certification only gets awarded to natural, high-quality diamonds. Diamonds that don’t measure up to this standard are rejected.


The Hoge Raad Voor Diamant (or Diamond High Council) in Antwerp, Belgium, is Europe’s leading authority in diamond certification, applying advanced techniques in their state-of-the-art laboratories. Each HRD diamond certificate also comes with security features to protect against counterfeit certificates.


Gemological Science International (GSI) offers GSI diamond certification and origin testing services to manufacturers and retailers all over the world. It also has a dedicated division that specializes in grading reports for colored gemstones.


Gem Studies Laboratory is an Australian-based organization that offers diamond grading and gem testing. All diamond certification and gem authentication reports from the GSL comply with established world standards.

Frequently Asked Questions

What is a diamond certification?

A diamond certification is a quality assurance report awarded to diamonds that meet certain standards in terms of their carat weight, color, clarity, and cut.

How to get a GIA certificate for my diamond?

To get your diamond certified by the GIA, it must be sent to an official GIA laboratory. The gemologists at the laboratory will perform an analysis of the stone, grade it, and issue a certificate. This certificate is referred to as a “diamond grading report”. Your local fine jewelry retailer is qualified to obtain a GIA report and explain its contents to you.

What is the highest quality diamond money can buy

Diamonds that are rated FL (“flawless”) for clarity and D (“colorless”) in terms of color are the highest-quality diamonds you can buy. However, D color diamonds and FL diamonds are exceptionally rare and are also very expensive.

Should I buy a lab-grown diamond?

There is nothing wrong with purchasing lab-grown diamonds. These diamonds are real, ethically sourced, conflict-free, and eco-friendly. They are also more affordable than diamonds that have been mined naturally.

How can I verify my diamond certificate?

Most diamond certifications can be verified online via the website of the relevant grading institute. The GIA is the preferred diamond quality grading organization in the United States.

Is IGI the same as GIA?

The International Gemological Institute (IGI) is a gem grading institute that performs similar functions to the Gemological Institute of America (GIA) in that they both issue diamond grading reports and diamond certifications. The GIA diamond reports are usually held in higher regard within the American market, but both organizations have a good reputation within the jewelry industry.

Is GIA certification worth it?

You can be assured that GIA-certified diamonds are accurately assessed and graded, giving you peace of mind regarding the quality of your diamond purchase.

How are diamonds graded?

Diamonds are graded according to cut, color, clarity, and carat weight (the 4Cs). For example, the GIA color grading system is used to rate diamond color on a scale from D-Z, with a D color diamond being the highest color grade.

How does diamond grading work?

Every diamond certification entity and gemological lab has different standards for evaluating diamonds. Some use GIA guidelines, while others follow AGS or EGL standards. This means that diamond certificates differ across countries and institutions, which can sometimes impact the value of a diamond in one part of the world or another. However, diamonds are generally graded according to the 4Cs: cut, color, clarity, and carat weight.