- Loose diamondsbijoux image by WSC from Fotolia.com
According to the Gemological Institute of America, diamond quality is assessed through the Four Cs of cut, color, clarity and carat weight. It is important to note, however, that diamond quality is linked to rarity. In other words, the highest grades in each category represent the rarest possible state. Therefore, the more rare the stone's combination of the Four Cs, the higher the quality of the diamond. - A diamond's cut determines how well it sparkles. Diamond cut is judged on the physical proportions of the stone as well as the facet symmetry and surface polish.
Diamond proportions are the measurements of length and width, or diameter if the stone is round, as well as the total height of the diamond. It also includes the various angles used to create the diamond's shape. Each shape has an established set of ideal measurements and is assigned a grade of Poor, Fair, Good, Very Good and Excellent, based on its closeness to the ideal.
A diamond's symmetry is also assessed. The facets, the flat polished surfaces on the diamond, in each diamond shape have a desired size, shape and placement. Facet symmetry is graded Poor, Fair, Good, Very Good and Excellent dependent on the amount of visible symmetry.
A stone's polish assesses how well the surface of the diamond has been polished to eliminate scratches and other naturally occurring surface blemishes. This, too, is assigned a grade of Poor through Excellent. - Diamond color is an assessment of how colorless a diamond is. The less color, the higher the quality because colorless diamonds are more rare than colored stones. Any diamond not specifically described as a colored diamond is considered colorless. This is a slight misnomer since diamonds that fall into the colorless category can display light brown or yellow tints.
Diamond color is graded on a scale ranging from D, displaying absolutely no color, to Z, displaying a slight yellow or brown tint. The scale is broken down into the following categories: Colorless, Near Colorless, Faint, Very Light and Light Color. The Colorless and Near Colorless categories are higher quality than all other brackets, with Colorless being the highest. - Almost all diamonds have clarity characteristics. These are surface blemishes such as scratches and internal characteristics such as minerals and bubbles that are termed inclusions. The clarity grade of a stone represents how visible these blemishes and inclusions are under 10x magnification by a trained diamond grader.
The scales ranges from Flawless (FL), no clarity characteristics, to Included (I), clarity characteristics are visible to the naked eye, where Included is the lowest possible grade. Moving down the scale from Flawless, the grades are Internally Flawless (IF), where there are surface blemishes but no inclusions to Very Very Slightly Included (VVS) where, under magnification, a trained grader can barely discern any characteristics. The two remaining grades are Very Slightly Included (VS), somewhat more visible under magnification, and Slightly Included (SI), where inclusions are fairly visible under magnification. - The standard unit of weight for diamonds is the carat. Representing .2 grams, the carat is the weight, not the size, of the diamond. This weight standard was adopted by the United States in 1913. Again, the higher the carat weight, the more rare the stone and therefore the more valuable.
- The overall quality of the diamond is determined through the combination of the Four Cs. In other words, the highest quality diamond would possess a D color grade, a Flawless clarity grade and Excellent in all three cut categories. The carat weight is always just a personal preference. Conversely, the lowest quality diamond would be one with a Z color grade, an Included clarity grade and a Poor grade in each cut category.
previous post