Diamonds 101: The 4 Cs of Diamonds

Investing in a diamond is a milestone in many people’s lives. You are purchasing something that is beautiful, unique and, yes, expensive.

Picking your diamond may seem like a daunting task. How do you know you’re getting your money’s worth?

Luckily, thanks to the Gemological Institute of America (GIA), there is a universal method by which a diamond quality can be judged. The 4 Cs of Diamond Quality allow customers the security of an objective, unbiased rating of the diamond they are planning to purchase.

So what are the 4 Cs?

They are color, clarity, cut, and carat weight. Let’s break those down.


Surprisingly, this rating actually based on the absence of color. A “perfect” diamond (both chemically and structurally) seems perfectly clear and colorless. The less of a hue, the higher the value.

Color is rated by GIA on a D-to-Z grading system. D signifies a perfect, colorless diamond, while a Z-rated diamond has less value due to the presence of color.

The “color” of a diamond may be indistinguishable to someone who is not looking for it, but heavily impacts the quality (and therefore price) of the diamond.


Clarity is a little trickier than color. Because of the way diamonds form, they may have inclusions (internal characteristics) and blemishes (external) that affect the value, and sometimes appearance, of the stone.

GIA has a diamond clarity scale that is divided into 6 categories and then subdivided farther for a total of 11 grades. The diamond grades are:

  • Flawless (FL) – No inclusions and no blemishes visible under 10x magnification
  • Internally Flawless (IF) – No inclusions visible under 10x magnification
  • Very, Very Slightly Included (VVS1 and VVS2) – Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
  • Very Slightly Included (VS1 and VS2) – Inclusions are observed with effort under 10x magnification, but can be characterized as minor
  • Slightly Included (SI1 and SI2) – Inclusions are noticeable under 10x magnification
  • Included (I1, I2, and I3) – Inclusions are obvious under 10x magnification which may affect transparency and brilliance

The naked eye may not be able to tell the difference from one to the other, so it’s important to get an expert rating and opinion to make sure you get the quality you desire.


When you think about the cut of a diamond, you probably have an image of the shape of it in your head. But when GIA talks about cut, they’re rating how well the diamond interacts with light.

It takes great skill to cut a diamond so that it reflects light in a stunning fashion. GIA uses proportions to determine how a diamond interacts with light and gives it a grade from there.

This rating system is simpler than the last two: Excellent, Very Good, Good, Fair, and Poor.

The grade also considers the craftsmanship of the diamond and factors such as weight relative to diameter, thickness, and symmetry.

Carat Weight

The carat system is internationally uniform. The name comes from the carob seeds; they were used as counterweights in balance scales by gem traders in the beginning of the industry.

Technically, metric “carat” is 200 milligrams, but for GIA’s measurement purposes, each carat is subdivided into 100 “points.” This makes it so the diamond can be measured in decimals.

As you may guess, larger diamonds are typically more expensive due to their rarity. Sometimes, though, if the diamond is lower on the other 3 Cs, a heavier diamond will end up being less expensive than a lighter one.

Quality Diamond & Gemstone Jewelry in Frederick, Maryland

Do the 4 Cs have you confused? Contact the diamond experts at Gold Thumb Jewelry to help you pick a diamond that’s right for you!


« Return to Blog