Diamond Certification Types: Everything To Know

Ensuring your diamond is certified by one of the leading independent and recognised certification laboratories is essential for an unbiased assessment of the stone's quality. GIA, AGS, HRD, IGI & EGL are the leading grading bodies in the diamond industry, and are listed here in order of strictness. Today, expect most diamonds over 0.20 ct to be graded by one of these.

GIA Certificate
AGS Certificate
HRD Certificate

IGI Certificate
EGL USA Certificate
EGL Int. Certificate

Diamond Certification - Expert Tips

  1. As subtle differences in diamonds can have a massive impact on price, if you are offered self-certification or certifications from less stringent local grading bodies, it is generally because the seller can improve their margins by doing so. Please remember the comparison of such diamonds would NOT be like for like. Always demand a recognised international certificate to create a level playing field.

  2. Even amongst the 5 internationally recognised certificates, there are differences. In fact, the diamond industry benchmarks every diamond against the GIA's (Gemological Institute of America) strict standards. Comparing a diamond with a GIA certificate against an IGI or the weaker EGL is not an equal comparison. So like-for-like colors or clarity grading on EGL would be graded 2/3 grades lower if sent to GIA and therefore should reflect lower prices.

Diamond Laser Inscription

The 5 leading diamond certification organisations issue a unique number for every diamond, to protect the consumer. On most new GIA certificates and selectively on some other certificates, this number is laser inscribed in the diamond's girdle, and can be easily verified with a magnification loop. This assures you the diamond you are buying is the actual one.

Diamond Laser Inscription

Diamond Laser Inscription - The GIA diamond report number will be inscribed in the girdle.

Individual Grading Laboratories & Certificates

There are many diamond grading laboratories around the world all of which produce their own grading reports according to their own standards, and in some cases employ their own terminology. As certificates play a large part in determining the value of diamonds, it is important to understand the different grading systems and how they compare with each other:

The Gemological Institute Of America (GIA)

GIA Certification

GIA certification.

Robert M. Shipley, a successful jeweller in the 1920s, noticed a lack of expertise in the jewellery trade. With a desire to bring trust to the industry, he completed the Great Britain National Association of Goldsmiths gemological course. Then, he launched his own gemology course to certify jewellers. He also started a jewellers' guild.

In 1931, the first GIA gemological laboratory was established, creating standards for evaluating gemstones. As a nonprofit organization, the GIA offers gemology and jewellery research and education, along with grading gemstones worldwide. The GIA is based out of Carlsbad, California with office locations in 13 countries.

The GIA is the respected entity when it comes to diamond and jewellery grading and certificates. They're the most consistent lab in the business.

Types of certificates issued by the GIA

The American Gem Society (AGS)

AGS Certification

AGS certification.

Found in 1934 by GIA founder Robert M. Shipley, the AGS is a trade association of retail jewellers, independent appraisers, suppliers, and selective industry members. Members are held to a high code of ethics with emphasis on consumer protection and education.

The Society is based in Las Vegas, Nevada, along with the affiliated American Gem Society Laboratories (AGS) (founded in 1996) and the American Gem Society Advanced Instruments Division (founded in 2004).

The Society trains and certifies jewellers, gemmologists, and jewellery appraisers. Diamond grading is the specialty of the American Gem Society Laboratories and the Society has developed its own cut, color, and clarity standards.

Types of certificates issued by the AGS

The Diamond High Council - Hoge Raad Voor Diamante (HRD)

HRD Certification

HRD certification.

Founded in 1976 to meet the growing demand for reliable diamond certificates, the HRD is a non-profit organisation at the service of the Belgian diamond trade and industry. Since its foundation in 1976, the HRD Certificates Laboratory has expanded into one of the largest diamond certification labs in the world and maintains an excellent reputation for quality and objectivity.

Each diamond is examined independently by several experts withvery sophisticated machinery, such as spectophotometres, Dia-Mention systems, and cathode luminescence apparatus to ensure a high level of reliability.

Types of certificates issued by the HRD

The International Gemological Institute (IGI)

IGI Certification

IGI certification.

One of the leading gemological institutions in the world, the IGI was established in 1975 in Antwerp, with a sister laboratory in New York, and has since become the largest independent gem certification and appraisal institute renowned for its quality services, extensive experience and expertise. What originally began with just 3 staff members has expanded to over 250 professionals dedicated to a remarkable standard of excellence in Antwerp, New York, Bangkok, Mumbai and Tokyo.

The IGI issues more than 400,000 reports per year. Thousands of jewellers, retail stores, insurance companies, internet sales organisations, catalogue companies, accounting and securities firms and consumers rely on the IGI reports.

International Gemological Information, a division of IGI, was established in New York in 1981, as a source for unbiased appraisals of gems and jewellery. Like its parent company, IGI Information is totally independent of all commercial sales organisations and does not trade in diamonds or precious stones. Therefore IGI Information is able to provide objective and accurate appraisals and identification reports, alongside appraisal updates and estimates in case of damage.

Types of certificates issued by the IGI

The European Gemological Laboratory United States Of America (EGL USA)

EGL USA Certification

EGL USA certification.

EGL USA is owned and governed by a different entity to other EGLs and is one of the world's premier independent gemological labs. It has been offering services to the fine jewellery trade and consumers forover 25 years. The EGL USA group is comprised of four North American labs based in New York, Los Angeles, Vancouver and Toronto.

Types of certificates issued by EGL USA

The European Gemological Laboratory (EGL)

EGL Int Certification

EGL Int certification.

Founded over thirty years ago in Belgium, the EGL is committed to protecting the integrity of the jewellery trade and fuelling public interest through applied science, education, innovation, and exceptional services. The EGL has an international presence with laboratories based in Antwerp (1973), Johannesburg (1980), London (1981), Paris (1981), Tel Aviv (1982), Istanbul (1990), Seoul (1990), Mumbai (2003) and Cape Town (2007). It is sometimes referred to therefore as 'GL Worldwide' or 'EGL International': The same standards apply to all these labs, but differ from EGL USA.

The EGL is accredited with introducing new approaches to diamond grading, the practice of certifying diamonds measuring less than 1.00 carat in weight, and establishing the 'SI3' diamond clarity designation. The organisation is also recognised for conducting advanced research with renowned physicists, geologists, and mineralogists.

Types of certificates issued by EGL International