For most people, buying a diamond is a new experience, but that doesn’t mean it should be overwhelming. Understanding a diamond’s quality characteristics is straightforward and simple. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, almost no gem-sized natural diamonds are perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond’s coloration, a diamond’s color can either detract from or enhance its value. For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink or blue diamonds can be dramatically more valuable.
Grading the normal color range refers to a grading scale for diamonds in the normal color range used by internationally recognized laboratories (GIA & IGI for example). The scale ranges from D which is totally colorless to Z which is a pale yellow phrase.
- D – Absolutely colorless. The highest color grade. Extremely rare.
- F-E – Colorless. Minute traces of color can be detected by an expert gemologist. A rare diamond.
- H-G – Near-colorless. Color difficult to detect unless compared side-by-side against diamonds of better grades. An excellent value.
- J-I – Near-colorless. An exceptional value with slightly detectable warmth or tone.
- K-Z – Noticeable color.
Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal characteristics of a diamond called inclusions, and surface defects called blemishes. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. A clarity grade is assigned based on the overall appearance of the stone under 10x magnification.
The GIA [Gemological Institute of America] diamond grading scale is divided into six categories and eleven grades. The clarity categories and grades are:
- FL – Flawless – diamonds have no inclusions or blemishes visible under 10x magnification.
- IF – Internally Flawless – diamonds have no inclusions visible under 10x magnification, only small blemishes on the diamond surface.
- VVS – Very, Very Slightly Included – diamonds have minute inclusions that are difficult for a skilled grader to see under 10x magnification. The VVS category is divided into two grades; VVS1 denotes a higher clarity grade than VVS2. Pinpoints and needles set the grade at VVS.
- VS – Very Slightly Included – diamonds have minor inclusions that are difficult to somewhat easy for a trained grader to see when viewed under 10x magnification. The VS category is divided into two grades; VS1 denotes a higher clarity grade than VS2. Typically the inclusions in VS diamonds are invisible without magnification, however infrequently some VS2 inclusions may still be visible to the eye.
- SI – Slightly Included – diamonds have noticeable inclusions that are easy to very easy for a trained grader to see when viewed under 10x magnification. The SI category is divided into two grades; SI1 denotes a higher clarity grade than SI2. These may or may not be noticeable to the naked eye.
- I – Included – diamonds have obvious inclusions that are clearly visible to a trained grader under 10x magnification. Included diamonds have inclusions that are usually visible without magnification or have inclusions that threaten the durability of the stone. The I category is divided into three grades; I1 denotes a higher clarity grade than I2, which in turn is higher than I3. Inclusions in I1 diamonds often are seen to the unaided eye. I2 inclusions are easily seen, while I3 diamonds have large and extremely easy to see inclusions that typically impact the brilliance of the diamond, as well as having inclusions that are often likely to threaten the structure of the diamond.
Is the unit of measure used to specify a diamond’s weight. A carat is a small unit of measurement equal to 200 milligrams. Carat is not a measure of a diamond’s size, but rather a measure of a diamond’s weight. One carat can also be divided in 100 points. A .75 carat diamond is the same as 75 points or 3/4 carat diamond. Because larger diamonds are found less frequently in nature, they are more valuable. Therefore, a 1 carat diamond will cost more than twice a 1/2 carat diamond, assuming other characteristics are similar. The most important thing to remember when it comes to a diamond’s carat weight is that it is not the only factor that determines a diamond’s value. The diagram to the right shows the size of various carat weights of a diamond in relation to each other.
The way a diamond is cut, its width, depth, roundness, size and position of the facets determine the brilliance of the stone or, what we generally think of as sparkle. When a diamond is cut with the proper proportions, light is returned out of the top of the diamond (which gemologists refer to as the table). If it is cut too shallow, light leaks out of the bottom; too deep and it escapes out of the side.
There are several grading methods to help consumers determine the cut of a particular diamond. In general, these grades are:
- Ideal – Cut is intended to maximize brilliance. Ideal cut diamonds generally have smaller tables, complemented by a great deal of light dispersion, or fire. GIA’s Excellent-Excellent stones, as well as AGS 000 stones fall into this category. This category applies only to round diamonds.
- Premium – Also intended to provide maximum brilliance and fire. Premium cut diamonds can be generally found at slightly lower price points than Ideal cut diamonds.
- Very Good – Diamonds reflect most of the light that enters, creating a good deal of brilliance. With these diamonds, the cutters have chosen to stray slightly from the preferred diamond proportions in order to create a larger diamond.
- Good – Diamonds that reflect much of the light that enters them. Such stones result from the cutter’s choice to create the largest possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller Premium quality diamond. Diamonds in this range offer an excellent cost-savings to customers who want to stay in a budget without sacrificing quality or beauty.
- Fair & Poor – A diamond graded as fair or poor reflects only a small proportion of the light that enters it. Often these stones are bought and re-cut into Ideal or Premium cuts, such that a more brilliant stones is produce by sacrificing some weight.
Diamonds come in many different shapes. Often, the final shape is decided by the lapidary who cuts the stone based on the initial shape of the raw diamond and any flaws that must be removed. Most basic shapes can be enhanced with trimmed or rounded corners, additional facets, or other characteristics to increase the stone’s beauty.
- Round – By far the most popular and most researched diamond shape available today. For almost 100 years, diamond cutters have been using advanced theories of light behavior and precise mathematical calculations to optimize the fire and brilliance in a round diamond. In addition to being the most popular and researched shape, a round diamond will typically give you more flexibility in terms of balancing cut, color, and clarity grades while still getting the fire and brilliance you want.
- Marquise – Like the Emerald, the Marquise is a traditional shape. This is probably the fourth most popular shape behind the Round, Princess and Oval.
- Pear – Mostly used in pendants, the Pear shape diamond is shaped in a tear drop shape and has fairly good proportions to refract light well.
- Princess – A square cut diamond that has refractive properties almost near round brilliant. The princess is the preferred square cut shape over Radiant and Asscher.
- Heart – Hard to find due to low demand, but some people prefer a Heart shape diamond for sentimental purposes.
- Oval – Not as popular for solitaires, but very popular for three stone anniversary rings, with two matching diamonds on the sides.
- Emerald – A more traditional shape, the Emerald is not as popular as it once was, but still retains its old world elegance.
- Baguette – The baguette cut is named due to its long, rectangular shape after the French word baguette, for “long rod”. Used primarily as a side stone, the baguette cut shape is a step cut diamond that is similar to other square to rectangular shaped step cuts, such as the emerald cut.
- Trillion – This triangular-shaped diamond provides a unique choice for couples looking for that special diamond. Trillion diamonds are most frequently found as accent stones to emerald, radiant, or princess diamonds because of their ability to nestle snugly against the side of a larger stone without unsightly gaps, but a well-chosen trillion would also make an admirable center stone.