1800 993 697

Shop 8 Raby Bay Harbour 152 Shore Street West Cleveland 4163

ABN: 16 884 875 007


Adrian Lee

Diamond Cut Quality

Cut quality is the most important and complex component of the 4 C’s of diamond grading.  The cut quality of a diamond will directly affect all of the other diamond qualities.  When examining what the cut of a diamond is, it is more about the proportion and symmetry of the diamond’s facets than the actual shape of the diamond. 

The quality of a diamond’s cut will directly result in how much and consistently and evenly your diamond will sparkle, it will also impact on the weight to length ratio, the appearance of its colour and how well the inclusions are disguised by the facets.

Cut Quality Grading System

The purpose of a diamond is to refract and disperse light with a scintillating brilliant fire and the “Cut” grading system measures the ability of a diamond to do this.   The more precisely a diamond is cut to it’s ideal scientific proportions the better the light refraction performance of the diamond.

GIA grades a round diamond into three categories;

  • Cut
  • Finish
  • Symmetry

With grades of either;

  • Excellent
  • Very Good
  • Good
  • Fair or Poor

The Cut grade by GIA is an evaluation of the overall performance of the diamond and how accurate it is to scientific standards.  The Cut grade is usually reserved to round diamonds and not assessed with fancy shape diamonds. 

The Finish of a diamond is the grading of the surface of the diamond and how well it has been polished to remove graining and scratches. 

The Symmetry of a diamond focuses on the relationship between each of the facets, how evenly they are cut and the angular plain that they sit.  The more perfect this relationship the more intense and even the light is refracted from the diamond. 

Why is The Cut of a Diamond Important

Of all the gems in the world none has better light refraction or brilliance than a diamond.  

To discover the beauty of a diamond from the rough gem a master craftsman must still correctly cut a diamond into its polished form to extract its full potential. 

A diamond of perfect proportion will refract close to 100% of the light entering the gem and also exhibit the correct measurements for its weight.

The general terms often advised by jewelers when explaining cut is about the depth of the diamond being cut too deep or shallow allowing light to escape from the base of the diamond reducing the intensity of light refracted by the diamond.  Generally with modern diamond you would rarely ever see a diamond that is actually cut too deep or shallow and has more to do with the overall precision of the cut which is why most diamonds have good sparkle but only a Triple Excellent diamond will have a perfect cut. 

The most common issues you will find with a poorly cut diamond is having a smaller diameter to weight ratio reducing the appearance of the size or disproportionately angled or shaped facets which creates an uneven light performance.

As almost all diamonds exhibit at least a small amount of natural tinted colour it is the scintillation of refracted light and it’s separation into the colour spectrum that help to disguise the yellow or brown tint of the diamond.  The less light a diamond refracts the more apparent the tinted colour becomes, therefore the better the Cut the whiter a diamond will appear. 

Another purpose for the way a diamond is faceted is to help hide the inclusions within the volume of the diamond.  A precisely cut diamond with its greater display of light will conceal inclusions that would become more obvious in a poorly cut diamond.

The more a diamond diverges from the ideal proportions the more quality that is lost from the diamond and cannot be retrieved.  

Because there can be such an extension of effect over into the other C’s, Cut can make up to a 50% difference in price between similar sounding diamonds.  This is why it is important to understand exactly what you are buying, know what questions to ask and to make sure that the diamond has appropriate certification.

Search Wholesale Diamond Prices Online

Once you have decided on the type of diamond you would like to buy, our wholesale diamond search tool is a great place to start looking for quality loose diamonds in your budget.

The online diamond search inventory is an international list of available loose certified diamonds that will give you a great guide to the wholesale price of different quality diamonds to help make your selection.

Free Quote