GRADING

How can I improve the categories under light performance for a diamond?
How can I improve the proportion categories of a diamond?
Can you look at my company's stones to see how they perform? How can I improve my stones?
What is Brightness?
What is Brilliance?
What is Contrast?
What is Dispersion?
What is Durability?
What is Leakage?
What is Weight Ratio?
What is Tilt?
What is Carat Weight and how is it graded in the AGS Laboratories?
How does the AGS Laboratories determine the Clarity Grade of a diamond?
How does the AGS Laboratories determine the Color Grade of a diamond?
What are the factors that determine the Cut Grade?
Is there a Cut Grade for fancy shape diamonds?
Does the AGS Laboratories disclose if a diamond has been treated?
What is the experience level of the AGS Laboratories diamond graders?
How many graders examine each diamond to determine Cut, Color, and Clarity?
What is Cut?
Does the AGS Laboratories grade colored stones?
What is a Hearts and Arrows diamond?
Does the AGS Laboratories assign a Hearts and Arrows grading to each diamond?
What is Luster?
What is Polish?
What are Proportions?
What is a Culet?
What is Shape?
What is Symmetry?

How can I improve the categories under light performance for a diamond?
You can improve the categories under light performance by cutting your stones according to our cutting charts, which you can request at marketing@agslab.com or by visiting the trade section of our website and registering. Registration is free. The cutting charts show different combinations of the crown and pavilion angles that result in the different grades. There are certain "sweet spots" in the chart that are great areas to cut your stones. The light performance can also be improved by cutting the stone more symmetrically. Another factor to consider is the different ways to cut the upper girdle facets.
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How can I improve the proportion categories of a diamond?

1. The girdle thickness of a stone can be improved by recutting a stone.
2. The Culet size can be reduced to improve the grade.
   
3. The Weight Ratio of a stone can be improved by increasing the millimeter footprint of the stone as compared to the stone's Weight. Reducing the girdle thickness of a stone, while keeping the other proportions of the stone the same, can decrease the Weight of stone and that will be result in a better weight ratio.
   
4. The durability of a stone can be improved if the crown angle is measured 30 degrees or greater.
   
5. The tilt category can be improved by increasing the pavilion angle.

Can you look at my company's stones to see how they perform? How can I improve my stones?
You can email us the Sarin file (.SRN) of one or more of your stones. We can then analyze that stone to see how it performs and then we can make an assessment on how to improve your stones' performance. Top

What is Brightness?
The amount of white light returned to the observer. Top

What is Brilliance?
Brightness with positive contrast effects. Top

What is Contrast?
The light and dark patterns seen when observing a faceted diamond. It can be positive or negative in its optical effect. Usually caused by, but not limited to, the observer's head. Top

What is Dispersion?
The separation of white light into colors by refraction. Top

What is Durability?
Resistance to chipping or breaking. Top

What is Leakage?
Areas that do not return light. Top

What is Weight Ratio?
The millimeter footprint of a diamond versus its weight. Top

What is Tilt?
The point at which the girdle reflects in the table and is defined by the minimum pavilion angle allowed for each table size. Top

What is Carat Weight? Is Carat Weight graded in the AGS Laboratories?
Carat Weight is a diamond's physical weight measured in metric carats. One metric carat equals 0.200 g. or one-fifth of a gram. In more familiar terms, that is a little more than 0.007 of an ounce avoirdupois. Avoirdupois is the common weight system we use in the United States. For precision, the carat is further divided into hundredths, and each of those is called a point. In the AGS Laboratories, Carat Weight is measured using a digital scale. Top

How does the AGS Laboratories determine the Clarity Grade of a diamond?
Clarity is the degree to which a diamond is free from inclusions and blemishes. Inclusions are internal characteristics. Blemishes are external characteristics. Many diamonds have Clarity characteristics that can be seen only with magnification. For grading purposes, the Clarity grade is subjectively based on nature, location, size, quantity, and relief of the inclusions. A minimum of two graders grade each stone for the Clarity grade. Top

How does the AGS Laboratories determine the Color Grade of a diamond?
Color normally refers to where a diamond's Color falls within the range from colorless to light yellow or light brown. For grading purposes, the Color of a diamond is determined by at least two experienced color graders using a set of master diamonds. Top

What are the factors that determine the Cut Grade?
AGS Laboratories utilizes the AGS Cut Grade system, which is based on the overall performance of a stone, specifically in the area of light performance. When analyzing the overall performance of the stone, we take the following into consideration: light performance (contrast, leakage, dispersion, and brightness), proportion factors (girdle thickness, Culet size, Weight Ratio, durability, and tilt) and finish (Polish and Symmetry). Top

Is there a Cut Grade for fancy shape diamonds?
Yes, in 2004, AGS released their fancy shape Cut Grade research, which concluded five years of research by a team of diamond experts, optical physicists and mathematicians. The AGS Laboratories' Diamond Quality™ Document is the first diamond grading report to ever issue a fancy shape Cut Grade. Currently AGS Laboratories is grading the Square Princess, but other fancy shapes will follow. Top

Does the AGS Laboratories disclose if a diamond has been treated?
The AGS Laboratories screens every diamond for potential treatments such as High Pressure High Temperature (HPHT), fracture filling, and laser drilling. The AGS Laboratories will grade a HPHT treated stone if the fact of its treatment is disclosed upon receipt. The AGS Laboratories does not grade fracture filled diamonds. However, the AGS Laboratories does grade diamonds that have been laser drilled. The drilling is disclosed in the 'Comments' section of the AGS Laboratories reports. Top

What is the experience level of the AGS Laboratories diamond graders?
Each grader is required to pass the Gemological Institute of America (GIA) Diamond and Diamond Grading Courses. In the AGS Laboratories, several Certified Gemologists oversee the work of each grader. Top

How many graders examine each diamond to determine Cut, Color, and Clarity?
A minimum of two (2) graders analyzes each diamond factor. Top

What is Cut?
The jewelry industry refers to Cut in two ways:

1. As a reference to the shape, style and faceting of a stone.
2. How well a stone is fashioned (e.g., brilliance, fire and scintillation).

Does the AGS Laboratories grade colored stones?
No, the AGS Laboratories does not grade colored stones. Top

What is a Hearts and Arrows diamond?
This is an optical effect that occurs when a diamond cutter places all 58 facets on a round brilliant cut diamond in a very precise relationship to each other. Most of these diamonds' proportions fall within the AGS Ideal proportion ranges. Top

Does the AGS Laboratories assign a Hearts and Arrows grading to each diamond?
No, the AGS Laboratories does not assign a Hearts and Arrows grading to diamonds. Top

What is Luster?
Luster is the quality and quantity of light reflected from a gem's surface. Top

What is Polish?
Polish is the quality of the diamond's surface and edges. Top

What are Proportions?
Proportions are the size and angular relationships among the main parts of the diamond.

The AGS Laboratories diamond graders consider the following factors when evaluating Proportions: Table Size, Crown Angle, Girdle Thickness, Pavilion Angle, Culet Size. Top

What is a Culet?
A Culet is the point on the bottom of a diamond's pavilion. A diamond's Culet may be pointed or it may be blunted with a small facet. Top

What is Shape?
The Shape is the outline of the stone such as marquise, pear, or oval. Top

What is Symmetry?
Symmetry is the exactness of the balance and evenness of the diamond's shape and facets. Top