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Roy W. Macdonald FGA, DGA

Bespoke Jewellery Designer PO Box 100, Callander, FK17 8ZR Tel 07710 544321

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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.


Diamond Certification – The whole truth



A uncompromising comparison of the main Five Diamond Grading Laboratories



99% of all the Certificated Diamonds I would offer my Clients will be GIA Certificated and 50% of these will be Triple Ex


In a Nut Shell – Should a Diamond Cutter submit the same Diamond to five Diamond Grading Laboratories, he will be presented with at least three different Grades. Why this should be is as confusing as reading the detail of their credentials and credibility.

All of these Laboratories are basically independent commercial grading institutes and a couple are non-profit organisations. All produce Certificates that are an assessment of a diamond’s 4’C’s – colour, clarity, cut, and carat weight and along with other technical characteristics such as plotted diagrams of its clarity characteristics, graphic representation of the diamond’s proportions and the presence or otherwise of Fluorescence.

None of these Certificates attribute a Value to a Diamond nor would they be classified as a Valuation Document. The Certificate will assist greatly in the attributing of a Value to a Diamond by a Gemmologist or Jeweller.

The following information and connected pages have been compiled for your further reading and will hopefully provide a better understanding of which Diamond Certificate you should consider when purchasing your Diamond.





The Gemological Institute of America (GIA)

GIA logo

Headquartered in New York, the GIA was established in 1931 as a non-profit educational resource for the gem and jewellery industry. The Institute’s aim is to provide the industry and the public with an independent, objective opinion regarding the quality of the diamond and as an unbiased arbitrator of standards in diamond grading in order to secure the public’s trust. Every stone submitted for certification is meticulously checked by numerous professionals to ensure maximum accuracy and grading consistency for client protection.

GIA was responsible for developing the first internationally accepted Diamond Grading System with unbiased opinions of the quality of polished diamonds by applying uniform criteria to their grading. It also introduced the foremost diamond report in setting the standard for diamond quality documentation around the world.

GIA Example Certificate

Click to visit the GIA website.


GIA Diamond Grading Report

Documents the carat weight, clarity and colour grades of a diamond, as well as its exact measurements, and in the case of Round Brilliant cuts, a cut grade. To see an example, click on the certificate on the right.

GIA Diamond Dossier

Issued for diamonds weighing less than 1 carat.

GIA Coloured Diamond Identification and Origin Report

Describes colour grade and colour origin (i.e. natural or treated) of coloured diamonds of any size. A full colour image may also be requested as an additional service.


Further reading on GIA  



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

HRD logo

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 with very sophisticated machinery, such as spectophotometres, Dia-Mention systems, and cathode luminescence apparatus to ensure a high level of reliability.


HRD Example Certificate


Click to visit the HRD website



HRD Diamond Certificate

A certificate detailing the shape, measurements, carat weight, clarity, fluorescence, colour and finish grades of a diamond as well as a plotted diagram. To see an example, click on the certificate on the right.

HRD Diamond Identification Report

A simpler version of the diamond certificate detailing the same characteristics as above but without a plotted diagram.

HRD Diamond Colour Certificate

A certificate outlining the colour description, origin and luminescence of fancy coloured stones.


The International Gemological Institute (IGI)

IGI logo

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.

IGI Example Certificate

Click to visit the IGI website


IGI Diamond Report

A detailed analysis of the stone's characteristics, including carat weight, color, clarity, polish and symmetry, and proportions. A diamond diagram with plotted clarity characteristics is also included. To see an example, click on the certificate on the right.

IGI Diamond ID

A passport-sized document that contains the same detailed information as the Diamond Report, without the plotted diagram. This report is also available in a more compact credit card size.


Further reading on IGI







The American Gem Society (AGS)

AGS logo

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 (AGSL) (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, colour, and clarity standards.

Click to visit the AGS website.


AGSL Diamond Quality Document

A document evaluating the colour, clarity, carat weight, and cut of a diamond, including a detailed diagram plotting the diamond’s proportions and illustrating any present inclusions.

AGSL Diamond Quality Report

A report detailing the cut, colour, clarity, and carat weight of diamonds in both AGS and GIA terminology.



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

EGL USA logo

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 for over 25 years. The EGL USA group is comprised of four North American labs based in New York, Los Angeles, Vancouver and Toronto.

Click to visit the EGL USA website


EGL USA Diamond Certificate

EGL Example Certificate

A certificate evaluating the colour, clarity, carat weight, and cut of a diamond, including a detailed diagram plotting the diamond’s proportions and illustrating any present inclusions. To see an example, click on the certificate on the right.

EGL USA Diamond Analysis Report

A cut grade certificate issued for round stones only.

EGL USA Coloured Diamond Analysis Report

This is exclusive to EGL USA and is the most popular document for coloured diamonds.

EGL USA Coloured Diamond Origin Report

A comprehensive document outlining the details and origins of coloured diamonds.

EGL USA Coloured Diamond Analysis Report

A more compact version of the Diamond Certificate, created especially for the trade.


The European Gemological Laboratory (EGL)

EGL International logo

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 ‘EGL 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 one 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.

Click to visit the EGL International website

EGL International Example Certificate


EGL Diamond Certificate Report

A certificate evaluating the colour, clarity, carat weight, and cut of a diamond, including a detailed diagram plotting the diamond’s proportions and illustrating any present inclusions. To see an example, click on the certificate on the right.

EGL Mini Certificate

A more compact version of the Diamond Certificate Report.

EGL “CertiCard”

The most compact of EGL certificates, this details the information as in other EGL certificates on a credit card type of document.