How diamonds are graded


Diamonds, being the world’s most popular gemstone, have very meticulous guidelines as to how they can be graded. There are four main measures upon which they can be graded, cut, clarity, color, and carat. While there are many other measures that determine the value of a diamond, these are the most important. (If you are unfamiliar with the Four C’s of diamond grading, please view our diamond guide here.) These grades must be determined in a controlled environment to ensure quality control. Due to this, the same diamond would receive the same grade from someone in New York or someone in Israel.

The Gemological Institute of America developed the International Diamond Grading System in 1953 to produce a standard for which diamonds are graded. This standard is followed by most of the world today. The grading standards are:

1.   A diamond must be graded in natural northern sunlight between the hours of 10 A.M. and 2 P.M., or in artificial light simulating these conditions.

2.   A diamond must be graded with 10x magnification.

3.   A diamond’s color must be graded by comparing it to a set of master diamonds.

I took a trip to Ramat Gan, Israel to see for myself the largest diamond exchange in the world. The Diamond Tower in Ramat Gan is where many of the world’s diamonds are graded. Here are some of the pictures from my trip:

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A desk used for sorting diamonds

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A diamond about to be cut

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A diamond grader at work

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Diamond bruting – a process used to create a round girdle by grinding two diamonds together

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Diamond cutting machine

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Two workers cutting a diamond with a programmable machine