- Do not confuse this grading factor for a karat, which measures the purity of gold. A carat is the unit of measurement when referring to a diamond's weight. The GIA created a very precise system, dividing the measurement into 100 points which is expressed to the nearest hundredth. (For example, a diamond worth 60 points is equal to .60 carats.) Price increases commensurately with carats. However, the cost is determined by the other Cs of diamond grading as well.
- While colored diamonds are rare and valuable, the value of a white diamond decreases when the color within increases. A colorless stone has the highest purity, but to the untrained, naked eye it is hard to distinguish between a perfectly colorless gem and one with a slight yellow tint. The color scale is divided into four sections and referred to by letters: Grade D through F are colorless and pure; Grade G through J are near colorless; Grade K through M have a slight yellow tint; Grade N through Z have a noticeable yellow tint ranging from light (N) to dark, to brown (Z).
-
Clarity is the categorizing of a diamond's "birthmarks," which are natural, minor imperfections in the stone. A diamond's clarity can be adjudged flawless, internally flawless or different ranges of "slightly included." A totally flawless gem is scarce and very valuable, as most diamonds have blemishes. Since these marks are not easily seen, all divisions of the scale are determined through intense magnification.
The degrees of clarity, from worst to best, are Included (blemishes are easily seen and apparent); SI1 and SI2 (Slightly included; marks are visible); VS1 and VS2 (Very slightly included; there are minor blemishes); VVS1 and VVS2 (Very, very slightly included; the stone's birthmarks are hard to see, even under intense magnification); IF (Internally flawless; there is a very tiny amount of natural birthmarks); and FL (Flawless). - Cut is the structure of the diamond, made up of many facets (angles). It has three characteristics: brilliance, scintillation and fire. A diamond's brilliance is its ability to reflect light; stones ranking low in this category tend to look lifeless and boring. Scintillation refers to what the light does to the stone when it is moved; essentially it is what makes a diamond sparkle beautifully. Fire is how well the light shines through the facets of the diamond, displaying many colors of the spectrum.
- There are many different cuts of diamonds.The most popular ones, according to "The Improper Bostonian," are Round, a perfectly round, symmetrical diamond, with all facets angled toward the bottom; Cushion, a rectangular diamond with rounded edges; Emerald, a similar shape to the cushion but with cropped corners and horizontal facets, which make them a "step cut"; Oval, an elliptical shape with a typical ratio of length to width of 1.5:1; and Princess, a diamond with square, pointed corners.
Comments
glitterlover said
on 9/22/2009 Great information... One thing I'd like to point out that very few people realize is that you can't actually determine how a diamond measures up on the 4C's using the naked eye - it has to be sent to a laboratory to be accurately evaluated. That's why it's a good idea to get diamonds that come with diamond grading reports from GIA - they're an independent lab that, as you pointed out, invented the standards for grading diamonds that are used across the industry today! Hope this helps!