The Basics of The Four C’s
The most important physical properties to look for in a diamond are referred to as the “4C’s” – Carat, Clarity, Color, and Cut. The concept behind the 4C’s is that all of these qualities work together to create the best diamond.
Diamond Carat Size and the 4 C’s
Carat refers to the weight of a diamond is expressed in carats. The word carat originated from the carob tree – the tiny seeds of this tree are well known for their uniformity and consistent weight. Traditionally, diamonds and gemstones were weighed against these seeds until the system was standardized, and one carat was fixed at 0.2 grams.
One carat is divided into 100 points. A diamond weighing one-quarter of a carat can also be described as weighing 25 points or 0.25 carats or 1/4 carats. Points are generally not used to describe weights over one carat. The larger or more a diamond weighs, the rarer the stone is. For example, a 1-carat diamond is much rarer (and much more expensive) than two diamonds each weighing 1/2 carat each. On average, 250 tons of ore must be mined and processed to produce a one carat diamond of gem quality.
When considering purchasing a diamond, it is important to really understand both size and weight in terms of what appeals to your taste and budget. Weight tolerances are based on the FTC standards, mm vs weight. Here are some commonly acceptable weights. 1/4ct = .23ct-.29ct, 1/3ct = .30ct-.36ct, 3/8 = .37ct -.44ct, 1/2ct = .45ct-.47ct, 3/4ct = .70ct-.82ct, 1.0ct = .95ct-1.10ct
Note: Carat is a measurement of weight, not size and so the overall diameter (mm) can differ slightly, either larger or smaller than listed in the chart above. Images are not to scale.
A diamond’s clarity refers to how pure the diamond is internally in terms of being free of flaws. To determine a diamond’s clarity, an expert views it under 10x magnification. The number of flaws found internally is called inclusions and external defects are called blemishes. Inclusions can be a result of mineral deposits, irregular crystals, flaws or cracks. Blemishes include scratches or nicks on the outside of the diamond. Blemishes and inclusions are normally not visible to the naked eye. A diamond that is flawless has no inclusions or blemishes and is extremely rare. Generally speaking, the least amount flaws a diamond has – the greater the value of the stone. The Gemological Institute of America (GIA) and the American Gem Society (AGS) both have created a scale to grade the clarity of a diamonds. See Clarity Guide for the clarity scale.
Cut refers to not only the shape of the diamond but its proportions and finish, two key factors which determine the sparkle of the diamond. A diamond can only be cut by another diamond; therefore, the cut is completely in the hands of a skilled diamond cutter. See Diamond Cut Guide and Grading for grading metrics.
It’s possible to have two equal polished diamonds, both having the same carat size, color and clarity, yet they may look completely different. How is this possible? There are many different shapes and facets in a diamond. The way a diamond is cut affects the stone’s brilliance. A stone’s brilliance is greatly determined by the arrangement of facets.
To extract the greatest beauty from a diamond, the light should enter a diamond and be dispersed as it bounces inside, thereby producing the different colors and sparkly effect, and returning as much light as possible to the eye.
The most popular cut today is the round brilliant, however, there are many different cuts that are available as well. Some of these include Princess, Emerald, Pear, Marquise, and Asscher.
Although diamonds appear to be clear and without color, most diamonds have hints of yellow or brown. When referring to a diamond’s color, this generally means the internal color of a diamond. The GIA and AGS both have created a system to color grade diamonds. The GIA’s scale ranges from “D” to “Z” – from colorless to light yellow. The AGS’s scale ranges from “0” to “10” – from colorless to fancy yellow. See Diamond Color Guide for grading scale.
A diamond without any color is considered to be very rare and the most valuable.
Natural diamonds can also come in a variety of vivid color including yellow, pink, blue, green, red, orange and black. Fancy colors are evaluated in several ways. The first quality is the basic hue or color (the rarer the color, the greater the cost) of the diamond. The second is the stone’s intensity (the richness or saturation of the color). The third is the purity of the color (is the color bright and clear, or clouded). These color characteristics form the basis for determining a fancy colored diamond’s worth. The more intense the color, the rarer and more expensive the diamond. For example, a fancy light yellow diamond costs less than a fancy vivid yellow diamond of equal size, shape, and clarity.