Cut is possibly the most important factor in the Four Cs, because cut is what gives a diamond its brilliance. Cut is certainly the most misunderstood and controversial of the four Cs. When we talk about cut, we mean much more than the shape of a diamond. We are talking about the technicalities of exact angles, proportions, symmetry, and polish that affect the way a diamond handles light.
In short, how well a diamond is cut determines how well the diamond will shine.
How can you tell if a diamond is well cut? The most common answer is to talk about proportions: whether the stone is too shallow, too deep, or just right. But fine cutting is not just a matter of proportion. A well-cut stone is carefully and precisely crafted: all the facets are exactly where they should be and polished until they gleam. To be well cut, a diamond must have the right proportions, precise symmetry, and a fine polish. Diamond dealers refer to this as "make," and it is the only thing about a diamond's quality that can be controlled by man. A stone with fine make has been carefully fashioned by the cutter to maximize its potential.
Whether you choose an emerald cut, an oval, a marquise, or any other diamond shape, a well-cut diamond will reflect light back evenly in the face up position, with no dark areas. A well cut diamond returns the maximum amount of light to the eye as brilliance. A well cut diamond also displays dispersion or fire: spectral colors of light that add richness to its sparkle.
Because the round cut is more standardized than the others, cutters have argued for about a hundred years about the best possible set of proportions for a round brilliant cut. How deep should it be? How large should the table be? What combination of angles results in the best balance of brilliance and dispersion?
One particular set of proportions for the round brilliant called the "ideal cut" has become very popular. Is it the best? The industry is still actively debating this point. Not all diamonds that are exceptionally brilliant have these proportions, and not all diamonds with these proportions are exceptional when it comes to handling light. Ideal cut diamonds also look smaller than finely cut diamonds with other proportions because they are more deep and less wide than standard cuts.
Whether or not you choose a diamond with ideal proportions, don't forget to look at the quality of a diamond's symmetry and polish. These will be noted on all diamond grading reports as excellent, good, fair, or poor.
As you may have guessed, symmetry refers to how well the facets line up against each other, which determines how efficiently they will reflect and refract light between them. Polish, of course, refers to how well the diamond has been buffed to a smooth finish. Poor polish will dull a diamond's sparkle, which once again comes from its reflection and refraction of light. When a beam of light touches the surface of a diamond, some is reflected back to the viewer. This is known as "external reflection." As the rest of the ray penetrates the stone, it is deflected by the stone's density toward the center of the diamond. This is called "refraction." The ray is then reflected from the internal surfaces of the stone and back out the top. This is known as "internal reflection."
A diamond's weight in carats is one measure of its value, along with the other 3 of the "4 Cs:" carat weight, cut, color and clarity. Diamonds are among the rarest of materials on earth; every diamond, of every size and quality, has a definite value.
The size of a diamond is measured in its carat weight. One carat = 1/5 of a gram. Carats are further divided into 100 points. Diamond weight may sometimes be expressed in points or in carats: a "75 point diamond" weighs 3/4 of a carat.
Large diamonds are far more rare than smaller ones. Large diamonds are highly prized because of their rarity and because larger diamonds, when cut, have more brilliance. Carat for carat, a large diamond will cost more than a smaller one.
It is difficult to judge the carat weight of a diamond by its apparent size; diamonds of the same diameter may weigh more or less than each other because of the way they are cut
|The most widely used system for grading a diamond's clarity was developed by the GIA (Gemological Institute of America). Each grade and description was developed so that trained gemologists all over the world working with a ten-power magnification could all give a diamond the same grade.|
|FI - Flawless : No blemishes or inclusions- Ordinary wear could cause a flawless diamond to lose its flawless status, and therefore they are rarely used in jewelry.||IF - Internally Flawless : No inclusions and only insignificant blemishes - Diamonds, with no inclusions and only tiny scratches or pits that can be removed by repolishing, are classified as IF.|
|VVS-1 & VVS-2 : Very, Very Slightly Included, very minor inclusions that are difficult to see - The inclusions in this grading are so small that the average person will likely not find them under a ten-power microscope.
||VS-1 : Very Slightly Included : Small inclusions that are difficult to see - An average person has a very hard time finding inclusions on diamonds in this category when using a ten power microscope.|
|VS-2 : Very Slightly Included : Small inclusions that are somewhat easy to see - The inclusions on a diamond in this category are the same as those in VS1, but the inclusions are more numerous or larger.||SI-1 : Slightly Included : Inclusions that are easy to see - The unaided eye probably cannot see any inclusions|
|SI-2 : Slightly Included : Inclusions that are very easy to see - The inclusions of these diamondscan be seen through the bottom of the stone, but not normally through the top.||I-1, I-2, I-3 : Imperfect : inclusions that are obvious - The inclusions of diamonds in these categories are easily seen. Diamonds with an I3 rating often look shattered. I2 and I3 diamonds may have inclusions that could affect the durability of the diamond.|
The Colours of diamonds can vary greatly. Diamonds can be red, green, purple, blue, brown, yellow, and even black. The brightly Coloured diamonds are often called "fancy Colour." The Colour is determined by which trace elements can be found within the diamond and how they originated. The most valuable diamonds are those for which no Colour can be found in the stone. Such diamonds, however, arevery rare. Far more common are diamonds with a slight to obvious yellow tint.
A Colourless diamond is more valuable because it reflects 100% of the light back through the diamond.
The Colour Grading System
The most widely used system for grading the colour of diamonds was developed by the GIA (Gemological Institute of America). The system uses alphabetical letters ranging from D to Z+ to identify Colours.
In terms of price, D is the most expensive Colour while N through Z are the least expensive. Diamonds, that are yellow enough to receive the rating of Z+, are considered fancies and are not priced in this manner. Their price increases with the intensity of their Colour.
Diamonds with a grade between D and F are rare and therefore, the most expensive. They are often called "Colourless" or "collection." The difference between a D and F graded stone is a matter of transparency, where D is the most transparent. D, E, and F stones are Colourless to the naked eye.
Diamonds in the G though J area are called "near Colourless" or "white." A near Colourless diamond can also be worth a lot, as the average consumer will not even notice the yellow tints. A trained gemologist, however, will be able to detect the yellowish hue.
K through M rated diamonds, or "faint yellow," have a slightly noticeable yellow tint. These stones are more common and less expensive. Some people prefer the yellowish tint because of the warm tone it conveys.
Diamonds that have been graded N through have a noticeable yellow Colour and are therefore much less expensive.