The 4 Cs of Diamonds
Color, Clarity, Cut and Carat

So, what exactly is a diamond, anyway? A diamond is actually an extremely hard, usually clear type of crystalline carbon which is formed over millions of years. The process begins up to 120 miles beneath the earth's surface when, under the right conditions, carbon atoms in melting rocks bond together to form diamond gemstones.

Considering the extreme conditions under which diamonds form, it shouldn’t be surprising that these gemstones are among the world’s rarest and most highly prized. Consumers interested in buying loose diamonds will find these gems make a sound investment. Not all diamonds, however, are exactly alike. Each diamond, much like a fingerprint, can display very distinct characteristics that set it apart from others in appearance, quality and value.

Traditionally, the overall quality and value of a diamond is determined by four specific characteristics. Known as the 4Cs, the characteristics that define a loose diamonds quality are: Color, Clarity, Cut and Carat Weight. Each characteristic plays a role in how an individual loose diamond looks while also having an impact on its relative value.

When gemologists examine loose diamonds for certifications, the 4Cs are meticulously considered. Here is a closer look at each of the 4Cs and how the characteristics can affect a diamond’s quality, appearance and value:

Diamond Color

Diamonds are available in a variety of hues, from rare, completely clear diamonds, to those which have an obvious yellow or brown tint. Loose diamonds that are considered chemically pure and structurally perfect will have no coloration whatsoever. These diamonds tend to fetch the highest prices. When gemologists rate diamond color, they use a D-to-Z scale that is designed to measure the degree of colorlessness a particular stone displays. On the scale, a D rating represents completely colorless. The letter-based scale increases to Z with each grade demonstrating an increasing presence of color. It is important to note that many of the color distinctions gemologists assign to a loose diamond are so slight they are invisible to those with an untrained eye. The grades, however, can represent big differences in quality and pricing.

Find out more about diamond color.

Diamond Clarity

Considering the extreme heat and pressure required for natural diamonds to form, it is quite common for individual gems to display tiny, internal imperfections. Almost all diamonds, in fact, have some internal inclusions or external blemishes. Most diamonds have flaws that cannot be seen except through the use of 10x magnification. Tiny flaws that cannot be seen by the naked eye are not likely to affect splendor of the diamond. They can have an impact on quality and value though.

Clarity is rated on a scale that ranges from “flawless” to “included” with different grades representing the evidenced severity of inclusions and blemishes. The lowest-quality diamonds, for example, may have inclusions so severe they affect brilliance and transparency. Generally speaking, most diamonds with different clarity grades will look exactly the same to the naked eye, but will command differing quality rankings based on what is witnessed under magnification.

Read more about diamond clarity grading.

Diamond Cut

The cut of a diamond is the most important element in choosing a diamond. The cut includes the diamond's proportions and symmetry as well as the overall finish. The better the cut, the more brilliance the diamond will have as its facets come in contact with light. This characteristic is graded based on a five-point scale with “Excellent” representing the highest quality and “Poor” the lowest. Cut plays a very important role in determining a loose diamond’s quality and ultimate value.


Read more about diamond cut.

Diamond Carat Weight

Carats are the units of measurement used to weight diamonds. A diamond carat weighs 200 milligrams. Smaller diamonds are measured using the point system, with 100 points being equal to one carat. Generally speaking, diamond price tends to increase based on carat weight. This may vary, however, based on other characteristics. Larger diamonds typically are considered rarer and tend to fetch a higher price if the other characteristics included in the 4Cs represent quality. Keep in mind that two loose diamonds of the exact same carat weight can have two very different prices based on other factors related to the 4Cs.

Learn more about diamond carat weight.