The Gemological Institute of America (GIA) was established in 1931 as a non-profit institute and is known to be the world’s most recognised and trusted grading lab, with its reports representing an independent third-party opinion in diamond grading. In the 1950s, GIA created the 4Cs of diamond quality, including the D-Z colour scale and flawless–I3 clarity scale of a diamond. A GIA report also provides a poor to excellent grade for cut, polish and symmetry as well as a proportion diagram of a diamond. Most of eClarity’s diamonds are GIA-certified.

The American Gem Society Laboratories (AGSL) was established in 1934 by a group of independent jewellers and Robert M. Shipley, the founder of the Gemological Institute of America (GIA). It is the first lab to offer numerical cut grading for diamonds including fancy-shaped diamonds such as princess, oval and emerald cut. AGS has 11 Cut Grades (0-10). A “0” grade is representative of the most desirable Ideal Cut and a “10” represents a poor cut. AGS grades seven aspects of the cut of each diamond. These include the table diameter, crown angle, pavilion depth, girdle thickness, culet size, polish and symmetry. The first five of these are grouped under the term “Proportion”. Diamonds that score 0 in all three cut categories are premium cut diamonds emitting maximum light returns.

The European Gemological Laboratory (EGL) was founded in 1974 in Belgium and is popular for its lower cost and fast service. EGL introduced the SI3 grade as a clarity grade. It has a clarity scale of flawless, internally flawless, very, very slightly included 1 – 2, very slightly included 1 -2, slightly included 1 – 3, and piques 1 – 3. EGL also offers a wide range of certificates, including the full certificate, mini certificate and the Certicard TM. The full certificate includes information on the 4Cs of the diamond, proportions and polish, as well as an image of the laser inscription on the girdle of the diamond. The mini certificate includes all information found in a full certificate, but in a compact format. The credit-card sized Certicard TM also includes all information as in a full certificate, together with a digital picture of the diamond face-up and the laser inscription on the girdle of the diamond.

The International Gemological Institute (IGI) is the world’s largest independent gemological institute with its headquarters in Antwerp, Belgium, founded in 1975. It is also popular for its lower cost and fast service. It has a D to V colour grading and an IF to I3 clarity grading and provides quantitative information on the proportions of a diamond.

Hoge Raad voor Diamant (HRD) or Diamond High Council is a diamond institution based in Antwerp, Belgium. The Diamond Lab of HRD Antwerp was founded in 1976 to meet the growing demand for reliable grading of diamonds. Its reports are mainly found in Europe and Asia. It has a colour grading of exceptional white+ to tinted colour (yellowish). Its cut grade system includes the proportions and finish grade of the diamond: proportions has a grading scale from very good (most ideal) to unusual, while finish grade has a grading system of very good (most ideal) to poor. The report also includes the detailed proportions of the diamond.