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Diamond Basics, The “4 C’s”

The name diamond comes from the Greek “adamas”, meaning unconquerable.  Made of pure carbon, diamonds are the hardest natural substance known to man.  Every diamond is unique, with its own individual beauty.  Selecting the finest diamonds is an intuitive art: the work of a connoisseur rather than a scientist.

We at Parkville Jewelers evaluate the diamonds we purchase in two overall ways:

  • Quality, as defined by the “4 C’s”
  • Beauty, which involves going beyond technical grading to discover diamonds that have exceptional fire, life and brilliance.

The four most popular factors used to measure the rarity of a diamond are cut, color, carat weight and clarity.  The “4 C’s” selection criteria, introduced by DeBeers to consumers in 1939, is a valuable tool that will help educate you so that you can better evaluate the quality of the diamond(s) you purchase.

The 4 main factors (4Cs) used to measure the quality of a diamond are cut, color, carat weight, and clarity. The 4Cs are the universal method for assessing the quality of diamonds throughout the world and a diamond’s value is determined using all of the 4Cs.


The diamond color evaluation is based on the absence of color. A chemically pure and structurally perfect diamond has no hue and a higher value. The GIA D-to-Z diamond color-grading system measures the degree of colorlessness, with D being colorless. Naturally colored diamonds outside the normal color range are usually called fancy-color diamonds. These are either yellow or brown diamonds that have more color than a Z or they exhibit a color other than yellow or brown.


Diamond clarity refers to the absence of inclusions and blemishes. Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called ‘inclusions’ and external characteristics called ‘blemishes’. Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these. No diamond is perfectly pure, but the closer to pure, the better its clarity.

The GIA Diamond Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades:

  • 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


Diamonds transmit light and sparkle. Diamond cut means how well a diamond’s facets interact with light. Using the best cut (round, oval, marquise pear, etc.) for a diamond reflects in the stone’s final beauty and value. Of the diamond 4Cs, cut is the most complex and technically difficult to analyze. To determine the cut grade of the diamond, the facets and how successfully a diamond interacts with light are used for effects, such as:

  • Brightness: Internal and external white light reflected from a diamond
  • Fire: The scattering of white light into all the colors of the rainbow
  • Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond

Carat Weight

Diamond carat weight measures a diamond’s apparent size or how much a diamond weighs. A metric “carat” is defined as 200 milligrams. Each carat is 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, such as, a diamond that weighs 0.25 carats as a ‘twenty-five pointer.’ All else being equal, the diamond price increases with diamond carat weight because larger diamonds are rarer. Diamonds of equal carat weight can have different values/prices depending on the other 4Cs.

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