What Are the Four Cs of Buying Diamonds?

The Four Cs are the four characteristics used to determine the quality and value of a diamond: carat, cut, clarity, and color. The characteristics of a diamond are graded and categorized by the diamond industry to establish its retail value. Quality diamonds are graded by a qualified expert and carry a certificate of authentication.

The Fifth C: Conflict-Free Diamonds

A fifth C—"Conflict-free" or "Blood-Free"—has become increasingly important to many buyers in recent years. "Conflict" or "blood" diamonds refer to those that originate from a conflict zone, and may have been used unethically to finance war against a government or rival faction. Diamonds mined during civil wars in more than a half dozen African nations have been labeled conflict diamonds.

"Conflict-free" diamonds are mined in stable countries with more ethical business and labor practices, such as Australia or Canada, and are sold by reputable dealers or jewelry retailers. They are rated by the Kimberly Process Certification Scheme (KPCS) and are certified as conflict or blood free.

Key Takeaways

  • The Four Cs are the carat, cut, clarity, and color of a diamond and are used to determine its value.
  • Cut describes a stone's shape and facets, which make it sparkle; clarity measures its purity; carats measure its mass.
  • The most expensive of the "white diamonds" are perfectly colorless, while "fancy diamonds," which have hues, are among the scarcest.
  • The Fifth C refers to diamonds that are mined in stable countries, rated and certified as conflict free, and sold by reputable retailers.

The Four Cs Explained

Here's a look at what how diamonds, an ever-popular choice for wedding engagement rings, are valued. Before investing in one, it's important to learn how to be sure you are getting what you pay for. It will also help you make tradeoffs. For example, you may prefer a larger stone, but be all right with slightly less clarity or slight flaws. Look at the choices with a jeweler when you choose your stone.

Cut

A diamond’s cut, or its shape and facets—is what makes it sparkle. The more faceted the cut, the greater the sparkle. The most famous shape and cut, according to the Cape Town Diamond Museum, is the round brilliant, with 57 facets. Other popular cuts include the rectangular emerald cut (44 facets), the square princess cut (50 or 58 facets), the oval cut (56 facets), the slender marquise cut (58 facets), and the hybrid pear cut (58 facets).

Clarity

Clarity measures the purity of the diamond and the presence (or absence) of tiny flaws. The clearer or more flaw-free the diamond, the more brilliant and valuable it becomes. Internal flaws are referred to as inclusions, while external ones are called blemishes. Jewelers and gemologists use a scale from FL (flawless) to VVS (very, very slightly included) to SI (slightly included) to I (included), with number gradations for each category, to rate clarity.

Carat

A diamond’s mass, or weight, is measured in carats. A metric carat is 200 milligrams, and each carat can be subdivided into 100 points. Diamonds that are more than one carat are expressed in carats and decimals, as in a 1.25 carat diamond. The price per carat increases according to its size since large diamonds are more rare.

Color

Diamonds come in many colors and are categorized as either white—essentially colorless—or fancy. Because distinctions of color among stones are subtle, experience and training are required to color-grade a diamond. These variations make a major difference in diamond quality and price. Depending on the hue and intensity, a stone’s color can either diminish or enhance its value.

The number of diamonds being mined has dropped off from a peak in 2005, allowing sellers to raise prices.

The color evaluation of white diamonds is based on the absence of color. The Gemological Institute of America's (GIA) color grading scale is the industry's most widely accepted system. It categorizes diamonds on a scale of D to Z. All D-Z diamonds are considered white, even though they contain varying degrees of yellow and brown.

  • Perfectly colorless diamonds at the D end of the spectrum are considered the highest quality and the most expensive. Colorless or clear white diamonds are more desirable, as they allow the most refraction of light or sparkle.
  • Brown- or yellow-hued diamonds at the Z end of the spectrum are deemed the lowest quality. Brown diamonds with varying levels of intensity are the most common and are in oversupply. They have been marketed as Cognac, Champagne, or chocolate diamonds to increase their appeal.
  • Fancy diamonds are stones that exhibit other colors, as well as stones with a yellow intensity beyond Z. Those that come in tones of naturally saturated reds, pinks, blues, and greens are the scarcest.

Celebrities, royals, and stars can also influence demand, causing a temporary spike in prices for a particular color. A diamond that is in fashion may lose value when trends change.