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 color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.
GIA's 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 diamond 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.
This short video explains the GIA color scale and how GIA classifies a diamond with a letter grade from D-to-Z by comparing it to masterstones representing the color grades on the GIA scale.
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.
The GIA 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 clarity is extremely important.
This short video explains the GIA clarity scale and how GIA classifies diamonds with a clarity grade ranging from Flawless to I3 by using a 10X magnification loupe and a microscope to see and plot the diamond’s inclusions.
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), 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.
A diamond’s cut is crucial to the stone’s final beauty and value. And of all the diamond 4Cs, it is the most complex and technically difficult to analyze.
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.
This short video explains the GIA cut scale and how GIA classifies round brilliant cut diamonds with a cut grade ranging from Excellent to Poor by factoring in a range of parameters including the diamond’s proportions, culet size, girdle thickness, polish and symmetry descriptions.
Diamond Carat Weight Measures a Diamond’s Apparent Size
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 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 within the 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.
This short video explains carat weight and shows how diamonds are weighed in GIA’s lab on an extremely precise electronic scale.
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