Diamonds are one of the world’s most valuable natural resources, not to mention one of the most coveted gemstones. Diamanten are naturally created with a tremendous variety of characteristics that make each and every diamond unique. The many possible combinations of these characteristics determine a diamond’s overall quality and value. Recognizing the need for a universal grading system, GIA, the Gemological Institute of America, recognized as the world’s most respected institute for gemological research, developed the four Cs. The four C’s stand for Cut, Color, Clarity and Carat Weight. This internationally recognized diamond grading system revolutionized the diamond trade and is now used by almost every industry professional and diamond enthusiast around the world. Because the quality and price of each diamond varies so widely, it is crucial for consumers to be familiar with the four Cs as well. We’ve outlined the basics of this rating system below to give consumers the resources they need to make informed purchases.


A diamond’s cut can 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 with a specific effect on the following three attributes:

  • Brightness – the amount of light that the diamond reflects
    • Fire – the different colors of the spectrum that a diamond emits
    • Scintillation – the sparkle and brilliance created when a diamond is moved

In a well cut diamond, the light entering through the table (the top flat facet) and traveling to the pavilion is then reflected and diffused through the crown creating a desired effect. Unfortunately, with a poorly cut diamond, some of the light escapes through the girdle, dramatically reducing the diamond’s brilliance.

The quality of a diamond cut is primarily based on symmetry and polish, as well as the relationship between table size, crown angle and pavilion depth. In most cases, the more facets a diamond has, the more brilliance and sparkle it has. However, the depth of the pavilion also has a major impact. If the depth of the pavilion is either too deep or too shallow, light can be lost down the sides of the stone instead of being channeled through the crown.

The round cut brilliant diamond is by far the most common diamond cut, although many others are becoming more popular. The brilliant round cut was specially developed for use on diamonds and with its 57-58 well-proportioned facets its brilliance and sparkle is more apparent than most other cuts. However, with so many variations in diamond cuts, there are many combinations of proportions possible that directly affect a diamond’s beauty and therefore value.


Similar to the cut of a diamond, its color will either increase or decrease its sparkle and fire. Obviously, diamonds with less color reflect more light than those with a light yellow or brown hue. This and the fact that nature provides us with fewer of these colorless diamonds makes them more valuable and desirable.

Once again recognizing the need for a universal system, the GIA developed the diamond color grading scale, lettered DZ, which is the most widely used today. Diamonds are graded under very precise viewing conditions and are often compared to diamonds of a known color class to ensure there are few differences within a color class. A colorless diamond is grade “D” and the more color the diamond contains, the higher up its grade in the alphabet. “Z” grade diamonds are light yellow or brown in hue and therefore do not reflect light as well as a colorless diamond. Fancy diamonds, while most are irradiated and color enhanced, do not follow this grading scale and are often more valuable because they are extremely rare in natural color.

The most common color grades are G to I as they are more common in nature and much more affordable. Although diamonds of these qualities have a hint of colour, they are generally not visible to the naked and untrained eye. Likewise, diamonds in grades J to M can have a very faint shade of yellow, but with the right piece of jewelery and the right diamond cut, the color can look less obvious (although this is hardly the case initially). White gold or platinum settings typically require higher quality diamonds, while a yellow gold setting will offset the yellow tint of a lower quality diamond.

Most jewelers use the GIA Diamond Color Grading Scale [out] and clients are encouraged to do the same to better understand the subtle differences in a diamond’s color and to better appreciate a diamond’s quality and value.


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 that has the greatest impact on a diamond’s value since flawless diamonds are so rare. Natural diamonds are created deep underground under extreme pressure, so it is not surprising that almost all diamonds have minor imperfections. There are two types of imperfections – blemishes and inclusions. Flaws are external imperfections found on a diamond’s surface 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 at the center of the diamond.

GIA has developed a universal grading scale for diamond clarity, consisting of 11 grades. Diamonds are graded under 10x magnification, so most of the flaws that affect clarity are barely visible to the naked eye. In addition to the number, size and severity of the inclusions, the position and color of the inclusions are also taken into account when grading a diamond’s clarity. Because no two diamonds are the same, the properties of a diamond and its inclusions make it totally unique and are sometimes used like fingerprints to identify individual diamonds.

The rarest clarity grades are F or FL (Flawless) and IF (Internally Flawless), diamonds of these grades are much more valuable because they are not that common in nature. The next best cleanliness levels are VVS (very, very lightly included) and VS (very lightly included). These diamonds are more common and sought after because they are more affordable than flawless diamonds and yet have very small inclusions, most of which can only be seen by an experienced grader under magnification. Probably the most common purity level is SI (slightly included). Diamonds of this clarity are still considered “eye clean” and offer a cost effective alternative. The lowest clarity grade, I (imperfect), has more noticeable inclusions that can affect the diamond’s brilliance.

GIA defines their purity rating scale as follows:

  • Flawless (FL)
  • At 10x magnification, no inclusions or flaws are visible to an experienced sorter
  • Internally flawless (IF)
  • No inclusions and only minor blemishes are visible to an experienced grader at 10x magnification
  • Very, very light included (VVS1 and VVS2)
  • Inclusions are difficult for an experienced grader to see under 10x magnification
  • Very light included (VS1 and VS2)
  • Inclusions are clearly visible at 10x magnification but can be characterized as minor
  • Easily included (SI1 and SI2)
  • Inclusions are visible to an experienced sorter at 10x magnification
  • Imperfect (I1, I2 and I3)
  • Inclusions are evident at 10x magnification and can 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 referring to the weight of diamonds. A carat is divided into 100 points, so a 1/4 carat diamond is called a “25 point diamond”.

Although carat weight is also used to measure gemstones, it is a bit more complicated since gemstone types can have different densities. Because of this, a 6mm round alexandrite can have a carat weight of 1.30ct, while a 6mm round citrine can weigh as little as 0.70ct.

In spelling, carat is usually abbreviated to “ct”. For a multi-diamond piece of jewellery, the abbreviation used is ‘ct TW’, meaning total carat weight (the sum of the carat weights for each diamond), although this is usually abbreviated to ‘ctw’. The value of such a piece of jewelry may be less than the value of a similar item of the same carat weight and only 1 diamond. Diamond solitaires are much rarer and as such a 1 carat diamond solitaire ring is worth much more than a similar 1 carat ring with many smaller diamonds.

Similarly, diamonds of the same size and Opal carat weight may not have the same value as they may have better clarity or color. A diamond’s cut also affects its carat weight and value, as some diamond cuts have more volume than others.

The four C’s, as described above, are the main characteristics that affect a diamond’s value. Just as importantly, however, they classify the diamond’s unique beauty and standardize the grading system used to classify an individual diamond’s quality. We strongly encourage consumers to educate themselves on diamond grading and other related jewelry information.

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