Diamond Basics

If you have any questions regarding the information below, please call us at (860) 246-9858 or email us.

Diamonds are sold by the four C's:

Carat, Color, Clarity and Cut which determine the value. Compromising your standards on one of the C's will lower the quality of the entire stone.


Carat weight is literally the mass of the stone on a scale, and has nothing to do with the size of the finished stone. A carat is divided into 100 points which equals 1.00 carat; i.e., 3/4 = 0.75 carat and 1/2 = 0.50 carat.

Diamond Color

Diamonds are more commonly found in the tints of brown and yellow. The closer we can come to the absence of color, the more valuable the stone becomes. Although, "fancy" colored diamonds; i.e., pink, purple, blue and intense yellow or canary are also very rare and expensive. Armstrong Rockwell Fine Jewelry refuses to sell diamonds below the top seven-color spread D E F (colorless) to G H I J (near colorless). 





























Near Colorless

Faint Yellow

Very Light Yellow

Light Yellow



Our diamonds are available
in this color range.

Diamonds are most often found in these color ranges, and are what can be found in most mall stores. Diamonds past Z in color are Fancy, considered rare, i.e. intense yellow (once called canary yellow), pink, blue and so on.



Almost all diamonds contain natural internal characteristics and external blemishes which are referred to as inclusions. These characteristics determine the clarity. The fewer, the smaller and the location of the inclusions and/or blemishes in a diamond determine the rarity and increase the value. 


(The clarity grading below are with 10x magnification)













Free of Inclusions:
Extremely Rare
Very, Very Slightly Included:
Very Very Rare
Very Slightly Included:
Very Rare
Slightly Included:


Armstrong Rockwell will only sell diamonds in the highest ranges of clarity.

Diamonds are most often found in these clarity ranges, and are found in your basic commercial market.


We specialize in triple zero ideal cut round diamonds, where more of the original crystal is destroyed to make the finished diamond more perfect. This is the single feature that man has control over, and the most important factor when determining the beauty and value of the stone. The cut is more than the shape of the diamond; cut is proportion, symmetry, alignment and polish. The ten criteria graded by the American Gem Society (AGS) together with  Hearts on Fire® cutting technology allow the round brilliant cut diamond to display the maximum brilliance (white light return) and scintillation (colored light return) possible. When compared to any other round diamond, the Hearts on Fire® diamond exudes the finest play of light in the industry.


(Examples of poor proportion of cut)

Diamond Cut

Hearts On Fire® Diamonds

What makes our diamonds a TRIPLE ZERO cut by the American Gem Society © (AGS)?

Diamonds have always been cut for profit, in other words, to retain the highest carat weight. Our Hearts On Fire® diamonds, however, are cut for beauty.  There have always been scales for carat weight, color and clarity, but many laboratories have avoided the issue of grading cut. Just recently the American Gem Society©  has established guidelines regarding cut. There are seven criteria within the three evaluated categories of proportion, symmetry and polish that are assessed to determine the highest grade: a zero cut diamond. These seven factors, along with the highest level of the hearts and arrows pattern, are what enable a  diamond to achieve the highest level of quality available. 

The criteria are as follows:


1. Average crown angle: 33.7° to 35.8°.

2. Average pavilion depth: 42.2% to 43.8%.  

3. Average table diameter percentage: 52.4% to 57.5%. 

4. Average girdle thickness: Thin, medium, slightly thick. Girdles rated as thin, medium or slightly thick receive "0" for this portion of the examination. Very thin to extremely thin girdles receive a "1" to "7" rating, and thick to extremely thick girdles receive a "3" to "10" rating. (Anything in these ranges receives a "0" rating for this portion; variances above or below receive a rating of "1" to "10," respectively.)  

5. Culet size: Very small, small and medium. These receive a "0" rating. AGS has defined a new standard: pointed culets are now acceptable to qualify as "0" grades. 

With the mathematical factors decided, the lab turns to the more subjective side of evaluating cut.


6. Symmetry evaluations look at off-center culets or tables, and out-of-line or wavy girdles. Characteristics with less of an impact, such as facets that are misshapen or don't point properly, as well as "naturals" (unpolished surfaces of the original diamond crystal often visible on a short length of the girdle) are also considered. 


7. Polishing evaluations examine characteristics such as abrasions, bearded girdles, pits and polish lines. The AGS originally used charts that didn't allow any symmetry or polish flaws to be visible under 10X magnification, "but we realized that diamond cutting is an art and not a science," says Yantzer, the director of the AGS laboratory. Consequently, polish and symmetry are now rated by description, with a range from "0" to "10." Yantzer says polish and symmetry will only "drive" a grade if either is worse than the proportions. To merit a "0" grade or a "1" final grade, diamonds must exhibit superb polish and symmetry.

Here's how the cut grade numbers break down: 

"0" – Extremely difficult to locate under 10X magnification. 
"1" – Very difficult to locate under 10X. 
"2" – Difficult to locate under 10X. 
"3" – Relatively easy to see under 10X (not visible to the unaided eye). 
"4" – Easy to see under 10X (extremely difficult to see with the unaided eye). 
"5" – Very easy to see under 10X (very difficult to see with the unaided eye). 
"6" – Obvious under 10X (difficult with the unaided eye). 
"7" – Relatively easy to see with the unaided eye. 
"8" – Easy to see with the unaided eye. 
"9-10" – Obvious to see with the unaided eye. 
Once all seven factors are evaluated, the lab assigns its ultimate cut grade as follows: 

"0" = Ideal. 
"1" = Excellent. 
"2" = Very Good. 
"3" or "4" = Good. 
"5," "6" or "7" = Fair. 
"8," "9" or "10" = Poor. 

Laboratories and Organizations:

AGTA: American Gem Trade Association

AGS: American Gem Society

GIA: Gemological Institute of America

IGI: International Gemological Institute

IWJG: International Watch and Jewelers Guild

NAWCC: National Association of Watch and Clock Collectors

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We are currently members of the International Watch and Jewelry Guild © (IWJG),
The National Association of Watch and Clock Collectors © (NAWCC), the Jewelers Board of Trade © (JBT),
and the Connecticut and the National Jewelers of America Associations © (JA).

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