Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).

Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA International Diamond Grading System™, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).

Every diamond is unique. None is absolutely perfect under 10× magnification, though some come close. Known as Flawless diamonds, these are exceptionally rare. Most jewelers have never even seen one.

The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10× magnification.

  • Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification
  • Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification
  • Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification
  • Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification
  • Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification
  • Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance

THE 4 C's OF DIAMONDS: COLOUR

Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. (The exception to this is fancy color diamonds, such as pinks and blues, which lie outside this color range.) Most diamonds found in jewelry stores run from colorless to near-colorless, with slight hints of yellow or brown.

GIA’s color-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colorless, and continues with increasing presence of color to the letter Z, or light yellow or brown. Each letter grade has a clearly defined range of color appearance. Diamonds are color-graded by comparing them to stones of known color under controlled lighting and precise viewing conditions.

THE 4 C's OF DIAMONDS: CUT

The most popular diamond in the marketplace is the round brilliant. Experts estimate that this cut alone accounts for more than 70% of all diamonds sold today. The quality of a round brilliant diamond’s cut determines how much the diamond sparkles. To pick a diamond whose flashes of light enchant the eye, you need to know the 4Cs of diamond quality, the universal standard for judging diamonds: color, cut, clarity and carat weight. All else being equal, the better the cut grade, the more valuable the diamond.

Some professionals consider cut the most important C of diamond quality. A well-cut round brilliant delivers that unmistakable, stop-in-your-tracks light show that telegraphs “diamond” across a crowded room. If the diamond is well cut, most compromises in clarity, color and even carat weight can be forgiven. A diamond’s cut grade is also an indication of how well it was designed and crafted. So, understanding the diamond cut grade is key to picking a round brilliant that’s not only beautiful, but also the best value.

THE 4 C's OF DIAMONDS: CARAT

 

Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams.

Each carat can be subdivided into 100 ‘points.’ This allows very precise measurements to the hundredth decimal place. A jeweler may describe the weight of a diamond below one carat by its ‘points’ alone. For instance, the jeweler may refer to a diamond that weighs 0.25 carats as a ‘twenty-five pointer.’ Diamond weights greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as ‘one point oh eight carats.’

All else being equal, diamond price increases with diamond carat weight because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors of the diamond 4Cs: Color, Clarity, and Cut. 

It’s important to remember that a diamond’s value is determined using all of the 4Cs, not just carat weight.