The Center of Gemological Studies (C.G.S)
was established by Eli Dori in 1979 and offers group & individual gemological courses
according to the students preference.

This is the most prestigious, affluent and respected gemological center in the Israeli Diamond Center
and has taught thousands of students that are working in the diamond industry today.
The C.G.S was chosen by the Israeli Diamond Center to teach the future Members the gemological course.

Eli Dori, is a graduate gemologist (G.G) for the last 40 years, he graduated outstandingly in residence of GIA.
Hadas Dori Bar Moshe graduated gemologist with experience of over 25 years.
They will provide you a comprehensive and intensive gemological course,
in an intimate, pleasant and patient environment, that suites and is adapted to every student.

If you are interested in studying, developing and obtaining experience in the diamond field,
as well as requiring the best professional knowledge and practical grading,
our center is the right place for you!

Gemology Course
Grading And Evaluation
Of Polished Diamonds

The course is taught over a period of 50 hours that include theoretical material as well as practical work which includes the grading of over 100 polished diamonds by microscope and by loupe. The method by which grading is taught is according to the GIA and their terminology.

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A captivating and unique lecture about diamonds and the diamonds industry. From Marlyn Monro to "Mazal and Bracha" – Hadas Dori Bar Moshe will take you on a spectacular and entertaining journey to the world of diamonds and it's industry. A lecture that will reveal the hidden secrets and behind the scene stories of this intriguing world.

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About Hadas and Eli

Eli Dori

Eli Dori, B.A in economics and accounting from Tel-Aviv University, Graduated Gemologist (G.G.) outstandingly in residence of GIA in California (diamond and colored stones), writer of the book: "Gemology – The Diamond: Grading & Evaluation". In 1979 Eli Dori established the: "Center of Gemological Studies" in the Israeli Diamond Center.

Hadas Dori Bar Moshe

Hadas Dori Bar Moshe, MBA from Tel-Aviv University, Graduated Gemologist in the Israeli Diamond Center since 1992, has over 25 years of experience in grading diamonds and teaching gemological courses.

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The Center of Gemological Studies refers its' students who are looking for work to offices within the diamond industry and to gemological laboratories.

Rapaport Diamond Report

Rapaport Diamond Report

Rapaport Diamond Report (RDR) for polished diamonds is named after the Jewish American diamond dealer Martin Rapaport, or by his nickname: “Mr. Bow-Tie”, because he only wears bow-ties.   Rapaport Diamond Report In 1978 the RDR was first published. This

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The Polish of the diamond

The Polish of the diamond

When the polish of the diamond is not good it affects the brilliancy, the fire and especially the luster of the stone. There are 3 defects that can affect the polish of the diamond:   Polish Lines – These are

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The finish of the diamond

The finish of the diamond

Girdle Surface   Faceted Girdle – Uniformly divided into small and distinct segments. That’s the only girdle surface that the GIA grades. Polished Girdle – Appears smooth. Rough Girdle –    Appears uniformly white mat. This is a natural girdle. *

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