Diamond Grading Process

At the Gemological Institute Laboratory a diamond is handled with the utmost care and professionalism. This is always the case, from the initial point it is entrusted to us and until the final moment when it is returned to our clients with its grading results and certificate. By using advanced instruments as well as industry respected grading procedures, GIS assesses and grades each and every diamond according to the strict standards adhered, and which we are committed to maintaining.


Eight -Step Process:

All diamonds which are examined in our institute will go through a rigorous grading process.



The weight and measurement of a diamond starts as soon as your diamond is brought to our labs. We then issue each diamond with an identification number. To ensure objective grading, and client anonymity, this special ID number replaces all client information during the time in which the diamond moves through the laboratory. Once the process is completed, a receipt which includes the Identification number, as well as the initial weight and the measurements of all diamonds, is given to the customers to keep for their records.



Every diamond is scanned by DiamondSure™ or by DiamondView™. These machines will confirm whether your diamond is truly an authentic, natural diamond.


Weight and Measurements:

During the next step the diamond is weighed and measured not once but twice more with technologically advanced measurement tools, which are situated in a controlled environment. These devices are calibrated several times each day.


Cut Grading:

In order to properly calculate each diamond’s cut grade, several sophisticated methods are taken with the measurement devices, along with a visual assessment of the diamond’s girdle and culet sizes. There are a total of six cut grades, which range from ideal to unusual. All diamonds are visually examined to verify the accuracy of the cut grade, and afterwards are assessed visually for optical symmetry to conclude whether they display a “hearts & arrows” pattern.


Clarity Grading:

Afterwards, the diamond is analyzed with a microscope by at least three gemologists to determine the clarity grade based on the position, type, number, and size of the clarity characteristics viewed at 10X magnification. To help ensure objectivity, each examination is performed without the knowledge of the previous gemologist’s determination. All results of this analysis are stored in a computerized database.


Color Grading:

Each diamond is afterwards graded for color on a scale of D (colorless) to Z (light amounts of color).


Certificate Issuance:

Once the grading process is completed, the diamond makes its way to our documentation station. At this station we print a Diamond Grading certificate, or a Diamond Précis, which indicates all grading results. The results can be accessed electronically by our clients through our online account management system.