How Important Is Diamond Cut Grade?

A Quick Lesson Beyond the 4 Cs for Diamond Shoppers

The 4 Cs of diamond grading are not four Cs at all because the most important attribute is beyond the 4 Cs, beyond what the eye can see, it adds or detracts from a diamonds beauty and more importantly value more than any other variable in diamond grading.

The B in beyond stands for brilliance, the most important attribute of a gem grade diamond, in that the beauty of a diamond is actually the beauty of the brilliance of light. Inherently we all know this when we see a beautiful stone, but we dont know why. All diamonds appear beautiful and brilliant in the light of the jewelry store spot lights, but it is in the natural light that the difference can truly be seen between an excellent cut diamond and a poorly cut diamond.

Im speaking specifically in regard to gem grade diamonds, diamonds with color at J or above and clarity above SI-2. The brilliance (cut) is the most important consideration in the evaluation of quality. The cut can influence a diamonds value and price by as much as 25%. Until recently, it was the least documented or understood by the consumer when purchasing a diamond.

Cut, the proportions and finish, are what determine a diamonds optical qualities and cut (brilliance) grading assesses the nature of those optical qualities that make up diamonds brilliance the amount of light and the nature of and balance of light returned to the viewers eye. The cut of the diamond is also the unnatural feature of the stone, crafted by a human cutter, the artist, and the businessman.

The Rarity of Diamonds and Cut Dilemma

About half of the worlds diamonds are mined from central and southern Africa and the other half come from various countries such as Canada, India, Russia, Brazil, and Australia. Diamonds are usually mined from volcanic pipes deep in the earth, where the high pressure and heat provide the conditions necessary for diamond formation.

Following the technical mining process, the rough stones are shipped out to be cut and polished. Traditional diamond cutting centers are located in Antwerp, Amsterdam, Johannesburg, New York, and Tel Aviv. Centers have also been recently established in China, India, and Thailand.

When the rough reaches its location, the difficult task of cutting can begin. The cutting of diamonds requires not only a great deal of skill, but a great deal of specialized tools as well. Cutters must use special saws, blades, and grinders to cut a rough diamond into a brilliant stone. And even with modern machinery and techniques the cutting process always results in a dramatic loss of weight in the rough. In fact, is it rarely less than 50% of the total carat weight that is lost in the cutting and faceting process.

The cutter has two objectives when cutting a stone, although they often conflict with one another. The cutter wants to keep the most weight possible out of the rough, but also create a cut which is highly valued by the market place. Therein lies the dilemma, the trade off the cutting factory has to make, size and number of stones over cut quality. For obvious business reasons, the quality can often be compromised.

It is the rarity of diamonds that drive their value, the rarer the diamond, the higher the price. Rarity is defined by the combination of all the 4Cs, this is why an Ideal Cut diamond demands the premium pricing found in the market place. The most rough is lost when creating this rare and magnificent diamond, thus this cut is reserved for the highest quality color and clarity stones, only gem grade stones will be ideal cut. So while there are quality tradeoffs in color and clarity, due to the loss of rough, no other aspect affects value (and price) greater than cut.

Ideal Cut Diamonds

The Ideal Cut diamond is elusive because it is so technical in nature and cannot be seen by the human eye. For example, the parameters below define the Ideal Cut range,

Ideal Cut Parameters:

• Table Diameter: 52.4% to 57.5%
• Crown Angle: 33.7 degrees to 35.8 degrees
• Girdle Thickness: Thin to Slightly Thick (.51% to 2.95%)
• Pavilion Angle: 40.2 degrees to 41.25 degrees
• Culet: None (Pointed) to Medium
• Total Depth: 56.88% to 63.92%

You can learn more about Ideal Cut Diamonds in the Diamond Education Center.

In my experience, whats important for a consumer to be aware of is hidden flaws in a diamonds cut. When comparing two stones and one seems like a great deal, this is often where the discounting occurs (this and fluorescence, another topic). Or, worse yet, proper discounting has not occurred. If a consumer is not aware and merely compares color and clarity he/she may not get the full value unless they know to assess the cut. This does not imply that a diamond needs to be an Ideal Cut to be beautiful; on the contrary, many diamonds in lower cut grades are beautiful but you dont want to pay too much.

Ask for Documentation

The key to diamond shopping, ask for documentation on the diamond cut grade. GIA recently started including this on their certifications, AGS also has a cut grade. But to get the exact proportions, degrees, and angles a more detailed analysis is required. This is typically done on a Sarin Proportion Analyzer, which will provide exact measurements of any diamond even as small as .10ct.

So when asked, how important is cut grade, I always say it is the MOST important. It drives brilliance, beauty, price and ultimately long term value. At my company, Diamond Design Co. we focus on the cut of every stone, from the smallest to largest, each stone is hand selected, and prior to mounting, measured on a Sarin Proportion Analyzer and selected for ideal proportions and brilliance creating the most beautiful pieces of diamond jewelry.

Learn before you buy, read Beyond the 4Cs.

Jacqueline Hull is the President and CEO of Diamond Design Co. (DDC), a high end jewelry company located in San Francisco. DDC designs and manufacturers custom engagement, wedding and anniversary rings. Ms. Hull has been working with jewelers and clients since early 2000 and has written numerous diamond education pieces for Beyond the 4Cs and Diamond Design Co.

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