What You Need to Know About AGS and GIA Certification Before Purchasing a Diamond - Savvy

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The AGS has made a name for itself as a premier diamond grading company. We advise customers to look for an AGS certified diamond because it is one of the most dependable and reputable lab grading organizations (or a GIA certified diamond). Make sure to purchase your AGS diamond from a reputable dealer, such as Blue Nile or James Allen.


Background of AGS

The American Gem Society was founded in 1934 by a small group of jewelers who aimed to shield consumers from deceptive marketing and fraud in the diamond trade (AGS). When they did so in 1966, they were the first group to publish a diamond cut grading system.

Today, the AGS offers gemological expertise, research, consumer protection, and uniform diamond grading to retailers, jewelers, and consumers.

The AGS is one of the most reputable lab grading organizations in the world thanks to its clear and consistent grading.


What does AGS certified mean?

Each diamond is assessed by the AGS based on its characteristics. It generates a grading report with information on the cut quality, carat weight, and other factors. Examine every detail in an AGS diamond grading report to make sure you're purchasing what you thought you were.


Report of Diamond Quality

The grading and description of the diamond you're purchasing are provided in the AGS diamond quality report. For round brilliant, oval, emerald, princess, and cushion cut diamonds, a thorough analysis is provided.

The cut, color, clarity, and carat ratings of the AGS diamond are all stated in the report. Under Cut, there are further aspects like light performance, symmetry, and polish.


Important dimensions of the diamond's table, pavilion, and other parts are also visible. A graphic that displays the diamond's inclusions is also shown.

You can more easily assess the diamond to see if it's the stone you want to purchase by glancing at an AGS report.

To make sure that the AGS diamond report you received and the AGS database agree, you can even perform an AGS cert lookup. This makes the report the jeweler gave you more authentic.


Report of Gold Diamond Quality

Round brilliant diamonds receive special AGS gold diamond quality reports. There is a proportion-based report included that goes into detail about things like table size and girdle thickness. AGS uses 3D technology to more thoroughly assess Cut quality. Other factors like carat weight, color, and clarity are still fully analyzed and graded in the report.

Below is an example of a gold diamond quality report.

AGS Gold Diamond Quality Report Sample


Is AGS ideal better than GIA excellent?

The 4Cs and the diamond grading organization assess a diamond's authenticity and quality. The AGS and GIA are the most reputable and trustworthy organizations in the market when it comes to diamond certificates. The four fundamental facets of a diamond's structure and beauty are represented by the four Cs: cut, color, clarity, and carat. AGS assigns a grade to each C according to a scale, which aids in estimating the cost and quality of a diamond.

The criteria for determining Cut quality are the only distinction between AGS and GIA. The cut grading system for AGS is from 0 to 10 (along with descriptive phrasing), where 0 denotes ideal and 8–10 denotes poor. Excellent, Very Good, Good, Fair, and Poor are the grades on the GIA scale. A diamond that has received a Cut grade from the GIA or AGS is legitimate and trustworthy. They both show whether a diamond has a good cut. For instance, we advise only taking into account diamonds that are GIA Excellent or 0 or 1 on the AGS rating.

Other than Cut, the attributes that AGS or GIA grade overlap with one another depending on how they evaluate that diamond component.

The grade number and names can be somewhat off, but the scales are in agreement. Below, we compare the grading systems used by AGS and GIA.



Diamond Cut grade denotes the quality of a diamond's angles, dimensions, symmetrical facets, brilliance, fire, scintillation, and finishing touches.

The AGS and GIA assign different grades to cut. The AGS grades work by allocating a number and a descriptive word grade.

The AGS Cut Scale runs from 0 to 9, with 0 representing Ideal and 10 representing Poor:

AGS diamond cut scale

The grades of Ideal and Excellent show proportions and angles that have been trimmed for maximum fire and brilliance, depending on Shape.

It's crucial to understand that a top rating, like Excellent, doesn't automatically mean a brilliant diamond. Nearly 55% of diamonds purchased online have an Excellent cut rating. Some are subpar, while others, like this 1.5 Carat Round Brilliant from James Allen, are breathtaking.

Reviewing Cut quality and getting a professional's judgment are vital because Cut is essential to a diamond's attractiveness.



A diamond's color grading describes how white or colorless it is. The color scale used by AGS to evaluate diamonds ranges from 0 to 10. (with 0 being the most colorless and 10 denoting noticeable yellow or brown tint).

The overlap between the AGS and GIA color grades is depicted in the chart below. You can compare the hues of two diamonds that have been verified by the GIA and the AGS using this chart.

AGS color scale

Even if the price difference between two diamonds with adjacent color grades may be noticeable, the naked eye can rarely tell them apart. Even though the AGS color grade aids in identifying the diamond's color quality, it's crucial to check whether the diamond is colorless to the unaided sight.

Note: Precious gemstones include fancy diamonds, such as a purple or blue diamond.

They have various color grades than conventional "white" diamonds.



Clarity is scored by AGS using a similar 10-point system as Cut and Color. A diamond's clarity grade describes how free of imperfections and flaws it is. How many flaws a diamond has are indicated by its clarity grading from the GIA or AGS.

AGS clarity scale

We advise selecting a diamond that is eye clean when considering clarity. Contact one of our experts if you're confused how to assess a diamond's clarity or any other quality.



Carat refers to a diamond's weight rather than its size. A 1 carat diamond weights 200 milligrams, or 0.2 grams, which is equivalent to about a fourth of a raisin. Depending on the diamond's shape and the way the gemstone is cut, two 1 carat diamonds may be fairly different in size.

When choosing which diamond to buy, the overall beauty of the stone should be given more weight than the carat size.



AGS reports also include information about a diamond's width, depth, and table size in addition to the 4 Cs.


Diamond Table Percentage

The breadth of the table (top surface area) is divided by its width to determine the diamond table percentage (diameter). The table percentage is 70% if the diamond is 5 mm wide and the table facet is 3.5 mm broad.

The shape of the diamond determines the optimal table. Get in touch with us and we'll be pleased to help you figure out whether a diamond has a high-quality table percent.


Diamond Width

The distance between the girdle's ends, which represent the diamond's diameter at its widest point, is used to calculate a diamond's breadth. When evaluating a diamond's length to width ratio, which establishes how proportional the stone is, width is crucial.


Depth Percentage

The diamond's depth % is calculated as its height measured from the culet to the top of the table. By dividing depth by width, one can calculate the depth percentage. Both millimeters and a percentage are used to express this quantity. A diamond with a depth percentage of 88.8%, for example, would have a width percentage of 4.5 mm and a depth of 4 mm.

Due of the increased width, a lower depth % of two equal carat diamonds typically seems larger. However, a depth percentage that is too low can provide the appearance of darkness since it will not effectively reflect light.

An AGS report also provides other information, such as finish, polish, symmetry, and fluorescence, in addition to the 4 C's and proportions.

These factors influence a diamond's beauty, although they are not the most crucial factors to take into account.


How Does AGS Certification Affect Cost?

The existence or absence of an AGS certification does not increase the cost of a diamond. The AGS is an impartial grading organization that has no financial interest in the diamond sale. The cost of AGS-certified diamonds is comparable to that of GIA-certified diamonds.


We strongly advise looking for an AGS or GIA Certified diamond. We also advise customers to only buy diamonds from reputed dealers like Blue Nile or Jared.


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