The quality of a diamond is determined by the 4 C’s – cut, color, clarity, and carat.
Only four continents have known diamond deposits and there are a limited number of mines in operation today. On the continent of Africa, diamond mines are located in Angola, Botswana, South Africa, Zimbabwe, Tanzania, and Lesotho. Asian mines operate in Russia and India. Both Canada and the U.S. operate mines in North America, and Australia mines diamonds at three separate locations. Crater of Diamonds State Park, located in the state of Arkansas, is a rare example of a non-commercial diamond mine.
The quality of a diamond is determined by what is known as “the 4 Cs.” The 4 Cs refer to the gem’s cut, color, clarity, and carat weight. A diamond’s color, clarity, and carat weight are part of its natural state. Only the cut of the diamond is left for humans to determine.
Many diamonds have a subtle yellow or brown color to them. Stones that are clearer and closest to colorless are considered to be the most beautiful. The clarity of a diamond is related to its purity, or lack of imperfections. In their natural state, smaller diamonds are more common. Therefore, larger stones, measured in carat weight, are coveted and have a higher market value. Lastly, the cut of a diamond is just as important as the first three Cs. A poorly cut stone can ruin the worth of an otherwise highly valuable diamond.
White diamonds are valued for their lack of color. The closer to color-free the stone, the more worth it has on the market. Graduations of color in diamonds can be extremely subtle and are often unnoticeable to the untrained and naked eye. Diamonds categorized with the letters D, E, and F are considered to be exceptional white gems, with letters G through L signifying less valuable stones. Categories represented by letters M through Z are considered to be “tinted” diamonds.
Colored diamonds are graded on the intensity of their color, as opposed to lack of it. The most common colored diamonds are yellow, brown (champagne and cognac), blue, green, and pink. Diamonds sold for their color are labeled as “fancy” diamonds and some can rival exceptional white diamonds in cost.
Diamonds in different shades of the rainbow have become more popular in recent years. Unusual diamond hues, such as purplish-pink, yellowish-brown, and grayish-blue, and finding their way into the collections of the most notable jewelers in the world.
While in years past, only diamonds in shades of clear, pink, blue and yellow were seen on the fingers of the rich and famous, diamond colors that veer from the standard have become more fashionable and sought after.
Continuous diamond hue circle chart from the Gemological Institute of America (GIA). Courtesy of the GIA.
Imperfections within a diamond are call inclusions. Inclusions are problematic because they interfere with light’s ability to pass through the gem, which makes the diamond less brilliant and therefore, less valuable. The international scale for clarity rates diamonds on the number of inclusions as well as the size and placement of them in the diamond. Clarity ratings range from flawless, meaning there are no inclusions present in the diamond, to level 3 imperfect, which means dark inclusions can be seen with the naked eye.
Explanations for each category of clarity are as follows:
| FL | Flawless | No internal or external blemishes when examined under a 10x microscope. Diamonds in this category cannot contain internal graining that is reflective, whitish, colored, or which significantly affects transparency. |
|---|---|---|
| IF | Internally Flawless | No internal inclusions, but minor surface blemishes which cannot be removed with polishing, such as surface grain lines or natural and extra facets on the crown. Blemishes that can be removed by minor re-polishing separate the internally flawless from the flawless grade. |
| VVS1, VS2 | Very, Very Slightly Included | Minute inclusions, such as reflective internal graining, which are difficult to locate using a 10x microscope. |
| VS1, VS2 | Very Slightly Included | Small inclusions, such as small included crystals, which are visible using a 10x microscope. |
| SI1, SI2 | Slightly Included | Inclusions that can be seen easily under a 10x microscope, and may also be seen with the naked eye using a white background. Inclusions in these diamonds cannot be seen through the crown of the diamond. |
| I1 | Imperfect 1 | Inclusions can be seen with the naked eye and are quite obvious under a 10x microscope. |
| I2 | Imperfect 2 | Inclusions can be seen with the naked eye and may interfere with transparency and brilliance. |
| I3 | Imperfect 3 | Dark inclusions which are very noticeable to the naked eye, which interfere with transparency. Diamonds in this category may contain cleavages that are likely to worsen with wear. |
