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Diamond Cut Guide

What is Diamond Cut?

A diamond cut is a style or design guide used when shaping a diamond for polishing. Cut does not refer to diamond shape but the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly impacts a diamond's brilliance; this means if it is cut poorly, it will be less luminous.

When designing a diamond cut, two primary factors are considered. Foremost is the refractive index (RI) of a diamond, which, at 2.417, is fairly high compared with that of most other gems. Diamond's RI is responsible for its brilliance - the amount of incident light reflected back to the viewer. Also important is a diamond's dispersive power - the ability of the material to split white light into its component spectral colors - which is also relatively high, at 0.044. The flashes of spectral colours that you see in a diamond, often known as 'fire in a diamond', are a function of this dispersion and are apparent only after cutting.

Poorly cut diamonds are either too shallow or too deep, causing the light to refract away from the diamond instead of refracting back from the top of the diamond.

Diamond cut refraction image

Available Cut Grades

  • Ideal
  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor

For the expert, perfectionist or diamond connoisseur Ideal cut is the top characteristic to look out for when purchasing your diamond. Ideal cut diamonds are expensive but they get the best sparkle out of a diamond.

Polish and Symmetry

Polish and symmetry are two important aspects of the cut. The polish describes the smoothness of the diamond's facets, and the symmetry refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. It may constantly look like it needs to be cleaned. With poor symmetry, light can be misdirected as it enters and exits the diamond.

Buying Tips

  1. Don't under estimate the importance of diamond cuts. A well cut 0.90ct diamond for example could have the same width, and give out more brilliance and sparkle, as a poorly cut 1.00ct diamond. Ensure you buy only Good cut diamonds or above.
  2. All diamonds used by Shining Diamonds are Good cut or above. However, if you have a specific requirement for a diamond cut please contact us for a customised quote