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Next up in the 4 Cs of Diamonds series is Cut

If you missed it, click here to check out the first blog of this series all about diamond color.

Photo credit: The Diamond Center

A diamond’s facets are the flat surfaces that form a wide range of geometric patterns, and “cut” refers to how those facets interact with light. Determining the cut grade is a highly scientific process and is the most difficult to analyze of the four Cs. The diamond cut grades are as follows: Excellent, Very Good, Good, Fair, and Poor.

Cut is the only C that is not a product of nature. A diamond is first cut from a large stone and its facets are carefully designed to enhance brilliance and sparkle. Brilliance refers to the diamond’s ability to reflect light back to the human eye and is measured by the cut. The more precise the cut, the greater the amount of light reflected and refracted by the diamond. The facets cut into a diamond interact with light to create an array of visual effects that include:

  • The facets of a diamond work in unison to maximize the amount of light reflected and refracted, within and without.

    Brightness: white light reflected internally and externally.

  • Dispersion: the scattering of white light into each color of the spectrum, also known as fire.
  • Scintillation: the amount of sparkle in a diamond, or the quick flashes of color seen as a diamond moves.

Cut is all about the science of proportion, perfectly balancing each facet amongst all the others to create the most dazzle and shine within the diamond. A poorly cut diamond, even one ranked high for clarity and color, will look dull and dark because the light within is not utilized to its full effect.


Watch the video below to hear what Joslin’s Jewelry’s very own diamond expert, Gary Joslin, has to say about diamond cut!