Diamond Certification: The Differences Between GIA, IGI, HRD, and AGS Certificates

As mentioned in a previous article on our blog, diamond certifications are documents that, in addition to confirming their authenticity, outline their characteristics through special grading scales. The certificate also specifies the proportions, and sometimes includes a mapping of any inclusions. This last feature, in addition to providing insights into the stone's origin, also ensures that the certificate corresponds to that specific stone.

Diamond certification: how important is it in the market?

It’s quite rare for an individual to buy a diamond without a certificate, not only because of the risk of getting a fake, but also because the price of a stone is mainly determined by its characteristics and their classification. So, the certificate not only confirms authenticity but also gives an idea of its market value: it tells us exactly what we’re buying. The same goes for selling: if we want to sell a diamond, the certificate tells us exactly what we’re selling.

Given the potential impact on the market, it’s crucial that diamond certifications come from highly specialized and, most importantly, impartial organizations—meaning they should not be affiliated with jewelry stores, auction houses, wholesalers, etc. The main certifying bodies are GIA, IGI, HRD, and AGS. In this article, we will look at the differences between these certifications.

GIA Certificate

Founded in 1931 as a non-profit educational organization for the jewelry and gemstone industry, the Gemological Institute of America (GIA) aims to provide independent and objective opinions on the quality of diamonds. GIA owes its reputation to the creation of the first International Grading System, recognized worldwide: the famous 4Cs:

• Cut
• Clarity
• Color
• Carat 

There are three different types of GIA certification:

• Diamond Grading Report: It provides the carat weight, clarity, color grade, and measurements of a diamond. For round brilliant cuts, it also includes a cut grade.
• Diamond Dossier: Issued by the institute for diamonds weighing less than 1 carat.
• Colored Diamond Identification and Origin Report: It provides the color grade and origin (natural or treated) of a stone, regardless of its carat weight.

A small inscription (invisible to the naked eye) is made on the edge of the stone to mark the GIA certification.

Every year, GIA trains thousands of gemologists, and its standards are recognized worldwide as the benchmark for gemstone grading. The institute has assessed some of the most famous and significant stones in history. Because of this, a GIA certificate is seen as a mark of quality and prestige, often adding to the value of a diamond.

IGI Certificate

Like GIA, IGI is also able to provide different types of certification

• Diamond Report: A detailed analysis of the stone's characteristics—carat weight, color, clarity, polish, symmetry, and proportions—along with a diagram showing clarity characteristics.
• Diamond ID: A document containing the same information as the Diamond Report but in a passport-sized format, also available in a more compact credit card size.
• Hearts and Arrows Diamond Report: A report exclusively created by IGI to assess optical symmetry.

Due to its convenient formats, the IGI certificate is one of the most commonly used by jewelers. Moreover, IGI was the first institution to issue specific identification certifications for jewelry.

HRD Certificate

The certifications issued by HRD are as follows:

HRD evaluates diamonds based on the highest standards using sophisticated equipment, and obtaining an HRD certificate is no small feat. For this reason, it represents a genuine guarantee when purchasing diamonds as an investment.

AGS Certificate

Founded in 1934 by a group of jewelers, the American Gem Society (AGS) is known for being one of the first to develop reports for diamonds with specialized cuts (princess, emerald, oval, etc.).

AGS issues the following certifications:

• Diamond Quality Report: A comprehensive analysis of the diamond's characteristics (4Cs) offered for round, oval, emerald, princess, and cushion cuts. In addition to the cut, other features are also graded, including polish, light performance, and symmetry.
• Diamond Quality Report "Gold": This report is issued exclusively for round-cut diamonds. In addition to a complete analysis of the characteristics, it includes a report based on proportions, illustrating aspects such as table size and girdle thickness.
• Diamond Quality Report "Platinum": Another report dedicated to round-cut diamonds, focusing on light performance.

AGS was founded with the aim of protecting jewelry buyers. Companies that wish to join must meet the highest standards of ethics and workmanship and undergo regular evaluations. For this reason, the value of an AGS-certified piece of jewelry is never questioned.

What is the best certification for diamonds?

All the gemological institutes mentioned in this article provide certificates that are completely reliable. However, diamond grading is still a subjective process, and the same diamond could receive different ratings from two different institutes.

In general, it’s best to choose the certifying organization based on the stone and its intended use. GIA is perhaps the most thorough and should be considered for larger diamonds, as it may give a lower grade for details that are only visible under a microscope. IGI provides comprehensive yet easy-to-read evaluations and is one of the most commonly used for jewelry grading. HRD represents the highest standard and should be approached only if you’re certain of your stone's absolute quality. Finally, AGS is the leading institute for specialized cuts, the only one to offer reports exclusively focused on cut quality. It's also important to note that all certifications have an expiration date, ranging from 5 to 10 years.

If you intend to sell a diamond, it is essential to consult a qualified specialist who understands how to read a diamond certificate (as it’s not always straightforward) and can accurately assess its value. If you do not yet have a certificate, Auctentic offers a complimentary evaluation by a GIA-certified gemologist.