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Diamond Cut

What is Diamond Cut?

Diamond cut is one of the most important factors to consider when buying an engagement ring. A diamond cut refers to the style or design guide used when shaping a diamond for polishing.

Cut does not refer to the shape of the diamond but the symmetry, proportioning and polish. The cut of a diamond greatly impacts a diamond's brilliance. So, if a diamond is cut incorrectly, this can seriously affect the desirable ‘sparkle’ that is the staple feature of engagement rings and all diamond jewellery.

When choosing a diamond cut, two main factors need to be considered:

  • Refractive Index (RI) - A diamond's RI is responsible for its brilliance - which is the amount of incident light that is reflected back to the viewer. The refractive index (RI) of a diamond is a measurement of 2.417, which is fairly high compared to most other gems.

  • Dispersive power - Dispersive power refers to the ability of the material to split white light into its component spectral colours. Those 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, which causes the light to refract away from the diamond instead of refracting back from the top of the diamond.

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 the most expensive cut of diamond, but they also create the most sparkle.

Polish and Symmetry

The polish and symmetry of diamond cut are both very important aspects.

  • Polish – this refers the smoothness of the diamond’s facets. Without adequate polish, the surface of the diamond facet can appear dulled, and may also create a blurred, or dulled, sparkle.
  • Symmetry – this refers to the alignment of the facets of the diamond. Poor symmetry can cause the light of the diamond to be misdirected, as it enters and exits the diamond.

Diamond Cut Buying Tips

Don’t underestimate the importance of diamond cuts. For example, a well cut 0.90ct diamond could have the same width and still offer more brilliance and sparkle than a poorly cut 1.00ct diamond. So we recommend buying only Good cut diamonds or above.

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 customized quote or visit us in-store at our Hatton Garden or Brighton jewellery store.

Ideal cut diamonds create the most sparkle. These diamonds have exceptional proportions and perfect symmetry, so they reflect the most light.

Round cut diamonds offer the most brilliance. However, it’s important to remember cut and shape aren’t the same thing. Cut refers to the symmetry, proportioning and polish of a diamond.

Natural diamonds can come in a wide variety of colours including yellow, pink, red, orange and blue. However, coloured diamonds are extremely rare – far rarer than colourless diamonds. So, they are significantly more expensive.