Diamond 4 C's
THE 4 C's
* 1. Cut
* 2. Carat
* 3. Clarity
* 4. Color
The 4 C's represent the four variables that are used to calculate the quality and value of a diamond. Both rough and cut diamonds are separated and graded based on these four characteristics. As a consumer, your first step in shopping for a diamond should be to learn and understand the "four C's" diamond grading system. There is an important "5th C" as well: Learning the details about certified diamonds and GIA diamond certificates or "Diamond Grading Reports." This will help when you are comparison shopping for diamonds.
Diamond 4 C's
When jewelers judge the quality of a cut diamond, they often rate "Cut" as the most important of the "4 C's." The way a diamond is cut is primarily dependent upon the original shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation of the weight, and the popularity of certain shapes. Don't confuse a diamond's "cut" with it's "shape". Shape refers only to the outward appearance of the diamond (see Fig. 2 below).
When a diamond has a high quality cut, light enters through the table and travels toward the pavilion where it reflects from one side to the other before bouncing back out of the diamond's table toward the observer's eye (see Fig. 1 below).
The "Shallow Cut" and Deep Cut" examples in Fig. 1 show how light that enters through the table of the diamond reaches the pavilion facets and then leaks out from the sides or bottom of the diamond rather than reflecting back to the eye through the table. Less light reflected back to the eye means less "Brilliance". In the "Ideal Cut" example, most of the light entering through the table is reflected back towards the observer from the pavilion facets.
Keep in mind that the variance in proportions between an "Ideal Cut" and a "Poor, Shallow or Deep Cut" may be difficult to discern to the novice observer. Cut quality is divided into several grades listed below.
* Ideal Cut
* Premium Cut
* Very Good / Fine Cut
* Good Cut
* Fair Cut
* Poor Cut
Diamonds Certified By EGL or GIA Gemological Laboratories
Popular fancy cuts include the "Baguette" (bread loaf), "Marquise" or "Navette" (little boat), "Princess" (square outline), "Heart", "Briolette" (a form of Rose cut), and the Pear. The "fancy cuts" are generally not held to the same strict standards as Round Brilliants.
Diamond 4 C's
Balancing Cut and Weight
Sometimes cutters compromise by accepting lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. Since the per-carat price of diamond is much higher when the stone is over one carat, many one-carat diamonds are the result of compromising "Cut" for "Carat". Some jewelry experts advise consumers to buy a .99 carat diamond for its better price or buy a 1.10 carat diamond for its better cut. A 1.00 carat diamond is usually poorly cut stone. See the chart in (Fig. 3) for a millimeter to carat size comparison.
Diamond Carat Weight
Due to a diamond's high brilliance and dispersion of light, the color grading should be determined by examining the stone through the side of the pavilion, and not by looking at the top of the stone, as in our Fig. 6 example below.
Diamond Color Diagram 2
Note: Your screen resolution may alter the reproduction size of the chart below. This carat/millimeter sizing chart is meant for comparison purposes only.
Diamond 4 C's
* FL - "Flawless" no inclusions at 10 x magnification
* IF - "Internally Flawless" no inclusions at 10 x mag. - small blemishes
* VVS-1 - "Very Very Small" inclusions hard to see at 10 x magnification
* VVS-2 - "Very Very Small" inclusions. VVS1 better than VVS2
* VS-1 - "Very Small" inclusions visible at 10 x mag. - not naked eye
* VS-2 - "Very Small" inclusions VS1 is better grade than VS2
* SI-1 - "Small" or "Slight" Inclusions or "Imperfections" may be "eye clean"
* SI-2 - "Small" or "Slight" Inclusions or "Imperfections" visible to naked eye
* SI-3 - Inclusions large and obvious, little or no brilliance
All of the above grades of clarity reflect the appearance to an experienced grader when viewed from above at 10x magnification, though higher magnifications and viewing from other angles are used during the grading process. In "colorless" diamonds, dark inclusions will tend to create the greatest drop of clarity grade. In other colors pale inclusions may have greater relief (may stand out more) and may cause a greater drop in grade. The chart in Fig. 4 explains the GIA grading system for inclusions and imperfections.
Diamond Cut Diagram 1
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Considerations in grading the clarity of a diamond include the type, size and location of inclusions. For instance, Inclusions near or on the surface may weaken the diamond structurally and therefore reduce its value. On the other hand, it may be possible to hide certain inclusions behind the setting of a diamond (depending on where the inclusion is), thus minimizing any negative practical impact of the inclusion.
It is important to be aware of the fact that a clarity rating is sometimes achieved artificially. For instance, "laser drilling" involves using a laser to burn a hole to a colored inclusion, followed by acid washing to remove the coloring agent. The clarity grade is the grade after the treatment. The treatment is considered permanent and both the GIA and AGS will issue grades for laser drilled diamonds. Reputable vendors should disclose that laser drilling has been used.
Clarity is sometimes enhanced by filling the fracture much like a car windshield crack can be treated. Such diamonds are sometimes called "fracture filled diamonds". Reputable vendors disclose this filling and reputable filling companies use filling agents which show a flash of color, commonly orange or pink, when viewed closely. There is a significant price discount for fracture-filled diamonds. The GIA will not grade fracture-filled diamonds, in part because the treatment isn't as permanent as diamond. Reputable companies often provide for repeat treatments if heat causes damage to the filling. The heat required to cause damage is that of a blowtorch used to work on settings, and it is essential to inform anyone working on a setting if the diamond is fracture-filled, so they can apply cooling agents to the diamond and use greater care while working on it.
"SI-3" is a grade sometimes used in the diamond industry. The designation of SI-3 was popularized by the EGL (European Gemological Laboratory) grading office. Neither the GIA nor the AGS (American Gemological Society), the most reputable well known US labs, assign this grade. Diamonds of this low grade would be inappropriate for jewelry.
Diamond 4 C's
* D, E, F - colorless
* G, H, I, J - near colorless
* K, L, M - faint yellow or brown
* N, O, P, Q, R - very light yellow or brown
* S, T, U, V, W, X, Y, Z - light yellow or brown
In determining the color rating of a diamond, the Gemological Institute of America uses a scale of "D" to "Z" in which "D" is colorless and "Z" is yellow. Yellow color is caused by Nitrogen atoms trapped in the crystal. The chart in Fig. 5 explains the GIA grading system for stone color.
Diamond Color Diagram 1
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Colorless diamonds are priced higher than yellow diamonds. However, when a diamond's color is more intense than the "Z" grading, it enters the realm of "Fancy Color". In this case, the intensity of the color in the diamond plays a major role in its value. The value of a Fancy Color Diamond will surpass that of colorless diamonds if the intensity of the color is high and the color is rare. A diamond may come in all colors of the rainbow.
A fancy brown diamond may have low value, relative to colorless diamond. However, a fancy pink or blue diamond will command higher prices. Fancy-colored diamonds such as the deep blue Hope Diamond are particularly valuable.
Brown diamonds, which are generally less appreciated and sold at a greater discount if the color is readily visible, have become more common as Australian diamonds have entered the market.
80% of the diamonds produced are of too poor a quality to be cut as gens. These poor quality (discolored and less transparent) diamonds are used as industrial diamonds, where their extreme hardness is useful in cutting and grinding otherwise intractable materials (including other diamonds). Lately, gas-phase deposition processes have been devised that allow thin diamond films to be grown on some surfaces, greatly increasing the durability of some machine tools.
While the prices are higher for colorless diamonds, the exact color most valued by a consumer is a matter of personal preference, with some preferring the very transparent D-F range, while others prefer the "warmer" colors in the G-J range and still others prefer a clearly visible tint.
We specialize in Loose Certified Diamonds By EGL & GIA.
We have a Large Inventory of Diamonds available for you to view at anytime. We carry both certified and non-certified diamonds. If we do not have a particular diamond that you desire in stock we can arrange to have what you want available from one of our partners in New York within the next day. You may schedule an appointment or walk in any time to view our extensive selection. We also make special viewing arrangements to fit your schedule if need be.
Diamond Cut Quality
For a Round Brilliant Cut, there is a balance between brilliance and "fire". A diamond cut for too much "fire" looks like a cubic zirconia, which gives out much more "fire" than a real diamond. A well executed round brilliant cut should reflect the most light out from the tabletop and make the diamond appear white when viewed from the top. An inferior cut will produce a stone that appears dark at the center and in some extreme cases the ring settings may show through the top of the diamond as shadows.
In the past, the "Cut" quality of the "4 C's" was the most difficult part for a consumer to understand when selecting a good diamond because a GIA or AGS certificate did not show the important measurements influencing cut (i.e. pavilion and crown angle) and did not provide a subjective ranking of how good the cut was. Only a trained eye could see the quality of a good cut. All of that has changed with the new GIA "Cut Grading System".
The proportion and symmetry of the cuts as well as the quality of the polish are factors in determining the overall quality of the cut. A poorly cut diamond with facets cut just a few degrees from optimal will result in a stone that lacks the gem quality because the "brilliance" and "fire" of a diamond largely depends on the angle of the facets in relation to each other. An Ideal Cut or Premium Cut "Round Brilliant" diamond has the following basic proportions:
* Table Size: 53% to 60% of the diameter
* Depth: 58% to 63% of diameter
* Crown Angle: 34 to 35 degrees
* Girdle Thickness: medium to slightly thick
* Facets: 58 (57 if the culet is excluded)
* Polish & Symmetry: very good to excellent
Basic Diamond Shapes
The shape of the cut is a matter of personal taste and preference. However, the quality of the cutter's execution of that shape is of primary importance. The shape of the diamond cut is heavily dependent upon the original shape of the rough stone. The round brilliant cut is preferred when the crystal is an octahedron, as two stones could be cut from one crystal. Asymmetrical raw crystals are usually cut in a "Fancy" style. Several basic diamond shapes (Fig. 2) are listed below.
The "Round Brilliant" cut was introduced in the middle of the seventeenth century. The first Brilliants were known as Mazarins, and had only 17 facets on the crown. In the early 1900's the 58 facet modern Round Brilliant was developed (Fig. 2 far right below).