When it comes to diamond color, evaluation is based on the absence of color. Ideal, structurally perfect diamonds have no color (much like pure water)—this results in a higher value. The GIA D-to-Z diamond color-grading system measures colorlessness of stones in a controlled lab environment against a select few “masterstones.”
Many color distinctions are incredibly subtle, to the point of being imperceptible to the untrained eye. Regardless, this color evaluation has a large impact on diamond price.
Natural diamonds are created by the exposure of ancient carbon to incredible heat and pressure within the earth. This process often creates a variety of characteristics in diamonds—internal ones are called ‘inclusions,’ and external ones ‘blemishes.’
A GIA evaluation of diamond clarity determines the number, size, relief, nature, and position of these characteristics, and (consequently) how they impact the aesthetics of the stone. When selecting a diamond based on clarity, it’s important to consider that no diamond is perfectly pure.
The GIA Diamond Clarity Scale has 6 categories divided into 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
Diamonds are sought after for their remarkable light and sparkle. For this reason, a diamond’s cut is highly important. The GIA diamond cut grade is distinct from the common perception of diamond cut as it relates to shape (e.g. round, heart, oval, marquise, pear). Rather, it reflects how well a diamond is fashioned to interact with light. A diamond crafted such that its proportions, symmetry, and polish deliver the utmost degree of brilliance will ultimately result in greater beauty and value.
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.
Cut is the most challenging of the 4Cs to analyze, requiring carefully calculated proportions that impact the diamond’s face-up appearance. These calculations can determine optimal proportions for the most desirable visual effects:
- 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
Other design and craftsmanship factors are accounted for in a diamond’s cut grade, such as weight relative to diameter, girdle thickness, facet arrangement symmetry, and quality of facet polish.
Understanding Carat Weight
Diamond carat weight simply measures how much a diamond weight. Each metric “carat” equals 200 milligrams, and each carat is divided into 100 ‘points’ (permitting precise measurement to the hundredth decimal place). Diamonds measuring below one carat can be described by these points alone (e.g. a 0.5 carat diamond may be referenced by a jeweler as a ‘fifty pointer’), while stones weighing above one carat are expressed in both carats and decimals (e.g. a 1.05 carat diamond may be described as ‘one point oh five carats’).
Diamond value generally increases with carat weight because of the rarity and subsequent desirability of larger stones. However, the value of two diamonds with equal carat weight can vary substantially due to the other three Cs (Color, Clarity, and Cut). Carat weight is not at all the only deciding factor of a diamond’s value.