The Four C's of Diamonds
Diamonds are one of the world's most valued natural resources, not to mention one of the most highly desired gemstones. Diamonds are naturally made with an enormous variety of characteristics, making each individual Diamond unique. The many possible combinations of these characteristics determine the overall quality and value of a diamond. Recognizing the need for a universal grading system, GIA, the Gemological Institue of America, regarded as the world's most respected institue of gemological research, developed the Four C's. The Four C's stand for Cut, Color, Clarity, and Carat Weight. This International Diamond Grading System has revolutionized the Diamond trade and today is used by nearly every professional in the industry and Diamond enthusiasts across the globe. Because individual Diamonds vary so immensely in quality and price, it is vital for consumers to be familiar with the Four C's as well. We've outlined the basics of this grading system below, to help give consumers the resources they need to make educated purchases.
Cut
The cut of a diamond may be one of the most important of the Four C's, and can enhance the overall quality, value, and beauty of that diamond. There are many different cuts, each having a specific effect on the following three attributes:
Brightness - the amount of light the diamond reflects
Fire - the various colors of the spectrum that a diamond gives off
Scintillation - the sparkle and brilliance that is produced when a diamond is moved
In a well cut diamond, the light which enters through the table (the top flat facet) and travels through to the pavillion is then reflected and dispersed through the crown, creating a desireable effect. Unfortunately, in a poorly cut diamond, some of the light leaks out the girdle, which dramatically reduces the diamond's sparkle.
The quality of a diamond cut is based primarily on symmetry and polish, as well as the proportions of the table size, crown angle, and pavilion depth to one another. In most cases, the more facets a diamond has, the more brilliance and sparkle it will have. However the depth of the pavillion also has a huge impact on this. When the depth of the pavillion is either too much or not enough, the light can be lost out the sides of the stone instead of being directed through the crown.
The brilliant round cut diamond is by far the most common of the diamond cuts, although many othersare gaining popularity. The brilliant round cut was designed specifically for use on diamonds, and with it's 57-58 well proportioned facets, it's brilliance and sparkle is more noticeable than on most cuts. Yet with so many variations of diamond cuts, many combinations of proportions are possible, directly affecting the beauty of a diamond. To learn more about diamond cuts and the effect they have on the quality of a diamond, see the Common Diamond and Gemstone Shapes and Cuts section.
Color
Similar to the cut of a diamond, it's color will either increase or decrease it's sparkle and fire. Obviously, diamonds with less color will reflect more light than those with a light yellow or brown hue. This, along with the fact that nature provides us with less of these colorless diamonds, makes them more valuable and sought after.
Once again seeing the need for a universal system, GIA developed the Color Grading Scale which is most widely accepted today, using the letters D-Z. Diamonds are graded under very precise viewing conditions and often compared to diamonds of a known color grade to ensure very few differences within a color grade. A diamond absent of color is grade 'D' and the more color that is present in the diamond, the further along the alphabet it's grade travels. Diamonds with grade 'Z' will have a light yellow or brown tint, and therefore will not reflect light as well as a colorless diamond. Fancy Colored Diamonds, although most are irradiated and color enhanced, do not follow this grading scale, and often are more valuable because when naturally colored they are extremely rare.
The most common color grades are G through I, as they are more abundant, and much more affordable. Although diamonds of these grades do have a hint of color, it generally isn't visible to the naked and untrained eye. Likewise, diamonds graded J through M may have a very faint hue of yellow, but with the right jewelry piece and diamond cut, the color may look less obvious (although it barely is to begin with). White Gold or Platinum settings usually require higher grade diamonds, whereas a Yellow Gold setting takes away from the yellow tint of a lower grade diamond.
Most jewelers use the GIA Color Grading Scale below, and it's recommended for customers to do the same to better understand the subtle differences in color a diamond may have, and to better assess the quality and value of a diamond.
Clarity
According to the GIA, "diamond clarity refers to the absence of internal inclusions or external blemishes." Of all diamond characteristics, clarity may be the one with the greatest impact on a diamond's value, since flawless diamonds are so rare. Natural diamonds are created deep within the earth under extreme pressure, so it's not surprising that nearly all diamonds have of minor flaws. There are two types of flaws - blemishes and inclusions. Blemishes are external flaws found on the surface of a diamond, and include chips, nicks, and scratches, most of which occur during the cutting process. Inclusions are internal flaws such as bubbles, cracks, or other minerals within the center of the diamond.
GIA developed a universal diamond clarity grading scale consisting of 11 grades. Diamonds are graded under 10x magnification, so most of the flaws that affect the clarity grade are barely visible to the naked eye. In addition to the number, size, and severity of the inclusions, the position and color of the the inclusion are also considered when grading the clarity of a diamond. Since no two diamonds are alike, the characteristics of a diamond and it's inclusions make it entirely unique, and are sometimes used to identify individual diamonds.
The most rare clarity grades are F (flawless) and IF (internally flawless), diamonds of these grades are much more valuable because they do not occur often in nature. The next best clarity grades are VVS (very, very slightly included) and VS (very slightly included). These diamonds are more common and sought after because they are more affordable than flawless diamonds yet still have very little inclusions, most of which can only be seen under magnification by a skilled grader. Likely the most common clarity grade is SI (slightly included). Diamonds of this clarity are still considered "eye-clean" and provide an inexpensive alternative. The lowest clarity grade, I (imperfect), has more noticeable inclusions which may affect the brilliance of the diamond.
GIA defines their clarity grading scale as follows:
- Flawless (FL)
No inclusions or blemishes are visible to a skilled grader using 10× magnification
- Internally Flawless (IF)
No inclusions and only minor blemishes are visible to a skilled grader using 10× magnification
- Very, Very Slightly Included (VVS1 and VVS2)
Inclusions are difficult for a skilled grader to see under 10× magnification
- Very Slightly Included (VS1 and VS2)
Inclusions are clearly visible under 10× magnification but can be characterized as minor
- Slightly Included (SI1 and SI2)
Inclusions are noticeable to a skilled grader using 10× magnification
- Imperfect (I1, I2, and I3)
Inclusions are obvious under 10× magnification and may affect transparency and brilliance
Carat Weight
The weight of a diamond is measured in carats, with one carat equaling 200 milligrams or 1/5 gram. You may also hear the term "points" used when speaking of diamond weight. One carat is divided up into 100 points, so a 1/4 carat diamond would be referred to as a '25 point diamond.'
Although carat weight is also used to measure gemstones, it is slightly more complicated, since gemstone types may have different densities. Because of this, a round 6mm Alexandrite may have a carat weight of 1.30ct whereas a round 6mm Citrine may only be 0.70ct.
When written, carat is usually abbreviated as 'ct.' In a jewelry piece with several diamonds, the abbreviation used is 'ct TW' meaning carat total weight (the sum of the carat weights for each diamond), although that's usually shortened to 'ctw.' The value of such a jewelry piece may be less than a similar item of the same carat weight with only 1 diamond. Diamond solitaires are much more rare, and therefore, a 1ct Diamond Solitaire ring will be worth much more than a similar 1ctw ring with many smaller diamonds.
Similarly, diamonds of the same size and carat weight may not hold the same value, because one may have better clarity or color. The cut of a diamond also affects it's carat weight and value because some diamond cuts hold more volume than others.
Fancy Colored Diamonds:
Natural colored diamonds are an amazing example of nature's rare beauty. There are a few ways in which diamonds can become different colors naturally. One way a diamond can become colored is by a separate element replacing some of the carbon molecules as the diamond is being formed. For example when nitrogen is present during the formation of a diamond, the nitrogen molecules will bond with the carbon molecules giving the diamond a yellow or light brown color. Although in most white diamonds nitrogen is considered a flaw, when there is enough of it to give the diamond an even and consistent color, the gem's value and desirability is significantly increased. When the element boron is present during formation, the diamond can acquire a blueish green hue. The compression of a diamond can some times make it a red or orange color. Another way for a diamond to naturally become colorful is through natural radiation. Natural gamma rays or isotopes can sometimes knock carbon atoms off of the diamond lattice to create voids in the diamond which usually emit a blueish color.
Natural fancy colored diamonds are extremely rare. There are currently less than ten natural red diamonds on the market for sale. The largest of these is 5.11ctw and recently sold for over $8,000,000, or around $1.5 million per carat, well out of reach for most of us. Luckily for us, there is a way to create gorgeous colorful diamonds by reproducing in a lab what nature takes millions of years to accomplish.
The most common form of creating fancy colored diamonds is irradiation treatment similar to that which also occurs in nature. To do this, the diamond is bombarded with gamma rays, or neutrons and electrons, knocking carbon atoms off of the lattice, and thereby creating blue or green colored centers. All diamonds that are irradiated in this manner become a blueish-green or black color. After the diamond receives the irradiation treatment it can also be heat and pressure treated to create other colors such as brown, yellow, pink or orange. Fancy colored diamonds created by using this second treatment are usually referred to as being 'annealed,' meaning that they have been subjected to very high pressure and high temperature, causing the carbon lattice to deform and different hues to emerge.
Sometimes violet and other fancy colored diamonds have been subjected to certain dyes to create their colorful appearance. Many dyes or surface covers are vacuum sealed on the diamond, however all surface treatments and dyes can be removed, most with alcohol or sulfuric acid, or the color will simply fade over time. This is one of the many reasons why irradiated diamonds have become increasingly popular in the jewelry industry.
The majority of colored diamonds on the market have been irradiated or treated in some other way. Since the diamonds that are used to create fancy colored diamonds generally are those with a less appealing color naturally, irradiated and color-enhanced diamonds are quite affordable. This has made brightly colored diamonds available to the average consumer, and inspired creativity and uniqueness in many stunning jewelry designs. Their popularity is constantly growing and colored diamonds have transformed from a jewelry trend to a classic look desired by many.
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