The 4 C's
Origin of the Diamond 4Cs
Every diamond is a miracle of time and place and chance. Like snowflakes, no two are exactly alike.
Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. GIA created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut, and Carat Weight. Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world.
The creation of the Diamond 4Cs meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they were about to purchase.
Diamond Color Actually Means Lack of Color. The diamond color evaluation of most gem-quality diamonds is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. GIA's D-to-Z diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones, which are stones of established color value.
GIA's diamond D-to-Z color-grading scale is the industry's most widely accepted grading system. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z.
Many of these color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.
Diamond Clarity Refers to the Absence of Inclusions and Blemishes.
Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called 'inclusions' and external characteristics called 'blemishes.'
Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.
Examples of how Clarity characteristics are plotted on a GIA Diamond Grading Report:
The GIA Diamond Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades:
- Flawless (FL)
- No inclusions and no blemishes visible under 10x magnification
- Internally Flawless (IF)
- No inclusions visible under 10x magnification
- Very, Very Slightly Included (VVS1 and VVS2)
- Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
- Very Slightly Included (VS1 and VS2)
- Inclusions are observed with effort under 10x magnification, but can be characterized as minor
- Slightly Included (SI1 and SI2)
- Inclusions are noticeable under 10x magnification
- Included (I1, I2, and I3)
- Inclusions are obvious under 10x magnification which may affect transparency and brilliance
Many inclusions and blemishes are too tiny to be seen by anyone other than a trained diamond grader. To the naked eye, a VS1 and an SI2 diamond may look exactly the same, but these diamonds are quite different in terms of overall quality. This is why expert and accurate assessment of diamond clarity is extremely important.
A Diamond's Cut Unleashes Its Light. Diamonds are renowned for their ability to transmit light and sparkle so intensely. We often think of a diamond's cut as shape (round, emerald, pear, etc.), but a diamond's cut grade is really about how well a diamond's facets interact with light.
Precise artistry and workmanship are required to fashion a stone so its proportions, symmetry, and polish deliver the magnificent return of light only possible in a diamond.
To determine the cut grade of the standard round brilliant diamond - the shape that dominates the majority of diamond jewelry – GIA calculates the proportions of those facets that influence the diamond's face-up appearance. These proportions allow GIA to evaluate how successfully a diamond interacts with light to create desirable visual effects such as:
- Brightness: Internal and external white light reflected from a diamond
- Fire: The scattering of white light into all the colors of the rainbow
- Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond
GIA's diamond cut grade also takes into account the design and craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets. The GIA Diamond Cut Scale for standard round brilliant diamonds in the D-to-Z diamond color range contains 5 grades ranging from Excellent to Poor.
Diamond carat weight is the measurement of how much a diamond weighs. A metric "carat" is defined as 200 milligrams.
Each carat can be subdivided into 100 'points.' This allows very precise measurements to the hundredth decimal place. A jeweler may describe the weight of a diamond below one carat by its 'points' alone. For instance, the jeweler may refer to a diamond that weighs 0.25 carats as a 'twenty-five pointer.' Diamond weights greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as 'one point oh eight carats.'
All else being equal, diamond price increases with diamond carat weight, because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors of the diamond 4Cs: Clarity, Color, and Cut. It's important to remember that a diamond's value is determined using all of the 4Cs, not just carat weight.
Only one in every 10,000 diamonds possesses natural color and is referred to as a fancy color diamond. For this reason, fancy color diamonds are purchased almost exclusively for the intensity and distribution of the diamond's color. Criteria considered when purchasing a white or colorless diamond, such as cut proportions and clarity, are less important when purchasing a fancy color diamond. While colorless, near colorless, faint and light diamond colors are graded from the face-down position. Laboratory graders assess fancy color diamonds from the face-up or top view of the diamond. Graders evaluate the hue, tone, and saturation of each diamond.
- Hue - A diamond's overall body color
- Tone - A diamond's lightness or darkness in relation to body color
- Saturation - The intensity or degree of color
Secondary or modifying colors are also assessed, as they impact the overall hue of the fancy color. For example, a yellow diamond may have a green secondary, and will subsequently be graded as "Fancy Greenish Yellow." A blue diamond may have a grey secondary color, and will be graded as "Fancy Greyish Blue" and so on.
Fancy color diamonds are graded using the following terms:
- Very Light
- Fancy Light
- Fancy Intense
- Fancy Dark
- Fancy Deep
- Fancy Vivid
Trace elements, structural irregularities, and radiation generally cause fancy diamond color. Here is a breakdown of common causes of natural fancy diamond color.
- Yellow Diamonds - Presence of nitrogen
- Brown, Pink, and Red Diamonds - Colored graining, which results from structural irregularities in the crystal lattice--sometimes in combination with an impurity.
- Blue Diamonds - Presence of boron with possible presence of hydrogen
- Green Diamonds - Natural radiation
- Grey and Violet Diamonds - Most likely the presence of hydrogen (grey diamonds are known for high amounts of hydrogen, while violet diamonds are still being studied for exact cause)
- Black Diamonds - Dark inclusions or impurities, which are great in number and evenly distributed throughout a diamond
- Orange Diamonds - Structural irregularities in combination with the presence of trace elements like nitrogen, though exact cause of color is still being studied