The cut of a diamond determines its brilliance. There is no single measurement of a diamond that defines its cut, but rather a collection of measurements and observations that determine the relationship between a diamond's light performance, dimensions and finish. Most gemologists consider cut the most important diamond characteristic because even if a diamond has perfect color and clarity, a diamond with a poor cut will have dulled brilliance.
The width and depth can have an effect on how light travels within the diamond, and how it exits in the form of brilliance.
Too Shallow - Light is lost out the bottom.
Too Deep - Light escapes out the sides.
Ideal Cut - Maximum provides sparkle in a diamond!
This refers to the presence of inclusions in a diamond. Inclusions are natural identifying characteristics such as minerals or fractures, that appear while diamonds are being formed. They may look like tiny crystals, clouds or feathers. Inclusions are usually viewed at 10x magnification.
The position of inclusions can greatly affect the value of a diamond. Some inclusions can be hidden by a mounting, thus having little effect on the beauty of a diamond. An inclusion in the middle or top of a diamond could impact the dispersion of light, making the diamond less brilliant. Inclusions are ranked on a scale of perfection known as the clarity scale. The scale ranges from F (Flawless) to I (Included) and is based on the visibility of inclusions at 10X magnification. In addition each basic grade is followed by the number 1,2 or 3 to indicates the severity of the inclusion(s).
The basic rule of thumb is if you can see the inclusion(s) with your naked eye then it is an "I" grade stone. If you can't see an inclusion with your naked eye it is either an IF, VS or SI grade stone (AKA - eye clean) & will need to be viewed with 10x magnification loupe to further determine the grade. If you can easily see it with a 10x loupe then it falls somewhere into the SI grade & if a 10x magnification doesn't show the inclusion then you'll need further magnification to narrow the grade to VS or IF.
Acting as a prism, a diamond can divide light into a spectrum of colors and reflect this light as colorful flashes called fire. Just as when looking through colored glass, color in a diamond will act as a filter, and will diminish the spectrum of color emitted. The less color in a diamond, the more colorful the fire, and the better the color grade.
COLOR refers to the degree to which a diamond is colorless. The farther from colorless that a diamond's grade is, the less rare and therefore less valuable it is. Diamonds are graded on a color scale established by the Gemological Institute of America (GIA), which ranges from D (Colorless) to Z. Icy winter whites (D-I) look stunning in white gold or platinum. Warmer colored diamonds (J-Z) are more desirable when set in yellow gold. Color differences can be very subtle and grading is done under controlled lighting and compared against a ‘master’ for accuracy. This color chart is representative of the color grades of a diamond.
This 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.