Like snowflakes, no two are exactly alike.
of diamond education
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.
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 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.
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 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
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
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.
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.