Gem and Jewelry Training Center
The Gem and Jewelry Institute of Thailand
(Public Organization) ITF-Tower Building.
3rd Floor, Silom Road, Suriyawong
Bangrak, Bangkok 10500, Thailand

Tel: +66 2634 4999 ext. 306
Fax: +66 2634 4999 ext. 304

Mon - Fri: 09:00 - 17:00
Closed on Thai government public holidays

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Certified Diamond Grader Diploma Program (HRD)

diamond grading

Certified Diamond Grader Diploma Program (HRD)

In collaboration with the HRD Institute of Gemmology (the educational department of the Antwerp Diamond High Council), GIT is proud to offer the HRD Certified Diamond Grading Course, a three-week class that combines theory with practice, where students learn how to grade diamonds by means of a microscope as well as a loupe. Our intention is to teach students how to fully grade a diamond and give them insights in the interpretation of diamond quality and the underlying techniques and science with respect to a diamond quality report.

Qualifications needed

No previous gemological knowledge is required. Only an ability to read and write English.

Language of Instruction


Certificate Awarded

Upon successful completion of the course and exams, students will receive the HRD Certified Diamond Grader Diploma (CDG)

Course contents    
  • Introduction: Mineralogy and formation of diamond, diamond optics
  • Evaluating the 4 C's

    Carat weight

    - Weighing by means of scales
    - Rrounding off carat weight
    - Calaulating the weight
    - Correct weighing and interpretation of the caratage of stone

    - Identification of internal and external characteristics
    - Measuring internal characteristics
    - Basic principles of clarity grading by means of the microscope & loupe

    - Introduction to color and fluorescence of diamonds
    - Discussion of Standard light sources and equipment
    - Grading color and fluorescence by means of masterstones
    - Discussion of the origin of color as well as the different color treatments

    - Explanation of cut grading
    - Measuring proportions by using the proportionscope
    - Grading the cut: description and evaluating of proportions and finish
  • Diamond simulants, treated and synthetic diamonds
  • System for grading polished diamonds