Understanding The American Gem Society (AGS) Quality Grading System

Posted by BloggerOne September 24, 2013 Comments are off 397 views

Purchasing a diamond is not something to be taken lightly. People spend years trying to find that perfect gemstone for a ring or necklace. You should make sure that you find a fantastic gem that you are in love with and also one that has the level of quality that you want and can afford. The American Gem Society, or AGS, has a grading system that assesses the quality of diamonds, and grades them based on various factors including the diamond cut, color, clarity and weight.

Now, when you buy a diamond, you can easily ask to know how it fares in terms of the grading system, but unless you understand what those criteria mean, the information will be useless to you. We hope that we can guide you through the AGS grading system so that when purchasing a diamond for either fashion or investment, you know what you are getting, and you understand its true worth.


How are Diamonds Graded?

Diamonds can be most easily and accurately graded if they are loose (as opposed to set in jewelry) since they can be inspected much more closely. This is the only way diamonds can be graded on the AGS scale. Furthermore, if the metal that the diamond is set in has any sort of color, such as gold, it can make the diamond appear more yellow than it really is, which would throw off the diamond’s color rating.

A diamond is evaluated in terms of four properties: cut, color, clarity and weight, and is graded on a 1-10 scale. The highest quality is 0, and goes progressively lower in quality till 10. This makes understanding the grading of diamonds extremely easy once you are familiar with the system. Let’s begin with the first property that diamonds are graded base on.


The cut of a diamond is how well it has been cut into its current shape. The better it has been cut, the more brilliant it will look. Cut is evaluated from 0-10, 0 being AGS ideal rating, 1 being excellent, 2 being very good, 3-4 being good, 5-7 fair, and 8-10 poor. The cut of a diamond can really affect the overall appearance of the diamond and so it is extremely important for a diamond to have a good cut rating.



The color rating of a diamond evaluates how clear the diamond is. Now this could depend on personal preference, as some people may want a warmer diamond that is slightly yellow, but for the sake of quality evaluation, the less “yellow” a diamond has, the higher quality it is considered to be. On the 0-10 scale, the color rating of a diamond goes from colorless, to near colorless, to faint, to very light, to light, to fancy. Fancy refers to a diamond that has a bold coloration and is far from colorless. Color is extremely important, but some people really appreciate diamonds with a slight color.


The clarity of a diamond speaks to its ability to reflect light and sparkle based on the numbers of inclusions, or natural imperfections, it has. The closer to 10 that a diamond gets on the scale, the more included it is and the less luminous it will be. The clarity of a diamond is extremely important and will affect its overall appearance, so it is very important to get a diamond with clarity as close to 0 as possible.


Finally, the diamond is evaluated based on its weight. Diamond weight, as with other gemstones, is measured in carats, which are equal to 200 mg. The heavier the diamond, the higher price it will fetch. The weight of a diamond is completely up to personal preference. Larger diamonds can be flashier, while smaller diamonds are more understated. You must decide how big a diamond would be right for you.

The Complete Rating

Once each aspect of a diamond is evaluated, the separate scores are combined into one grading that orders the scores like so: Cut/Color/Clarity-Weight. For example, if a diamond received a perfect 0 in each category and weighed 2 carats, its grading would be written like so: 0/0/0– 2.000 carat.

This grading system is very simple once you understand how to read it, and what it means. It will greatly assist you to understand it when buying diamonds, and will help you to know exactly what to expect in a diamond. Before you buy a diamond, know the grade you wish to get and try to find one that matches your dream stone.

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Peter LaChance is a freelance writer based in New York City. He is a frequent content provider to Diamond Envy (www.diamondenvy.com)

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