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Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams.
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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. For example, a 1.08 carat stone would be described as 'one point oh eight carats'.
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All else being equal, diamond price increases with carat weight because larger diamonds are rarer and more desirable. However, two diamonds of equal carat weight can have very different values (and prices) depending on three other factors of the 4Cs:, Color, Clarity, and Cut. It's important to remember that a diamond’s value is determined using all of the 4Cs, not just carat weight.
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The 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.
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GIA’s D-to-Z color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to ‘master’ stones of established color value. This 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.
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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. At SFD, we strive to accurately grade our diamonds, so that our customers can be confident in their quality.
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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.’
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Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, and how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.
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The GIA Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades:
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No inclusions and no blemishes visible under 10x magnification.
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No inclusions -visible under 10x magnification.
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Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
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Inclusions are clearly visible under 10x magnification, but can be characterized as minor.
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Inclusions are noticeable under 10x magnification.
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Inclusions are obvious under 10x magnification which may affect transparency and brilliance.
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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 accurate assessment of clarity by our experts at SFD is extremely important.
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Diamonds are unique among gemstones in their ability to transmit light. That’s why they sparkle so intensely. We often think of a diamond’s cut as shape (e.g., round, emerald, pear), but a diamond’s cut grade is really about how well a diamond’s facets interact with light.
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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.
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Cut is crucial to the stone’s final beauty and value. And of all the 4Cs, it is the most complex and technically difficult to analyze.
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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:
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Internal and external white light reflected from a diamond.
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The scattering of white light into all the colors of the rainbow.
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The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond.
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GIA’s 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.
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The GIA Cut Scale for standard round brilliant diamonds in the D-to-Z color range contains 5 grades ranging from Excellent to Poor.
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