Below is taken as an example of some diamonds that were assigned different cut grades by the GIA. The concept of cut grade has many consumers baffled and there is huge confusion the in the market place as to the significance and importance of cut grade when buying a diamond engagement ring. My attitude to cut grade has always been “Beauty is in the eye of the beholder”. There are some symmetrical guidelines that outline cut grand in diamonds and these symmetry guidelines are what determine a laboratories decision to label a stone a certain grade. Generally it is a measure as to how effectively the diamond reflects white light. The problem is that many of the worlds best known and beautiful diamonds under these symmetrical guidelines would return a poor cut grade. Certainly a badly cut stone is easy to spot and there are many poorly cut diamonds out there but I would never advise on purchasing a diamond on cut grade alone. The difference to the naked eye between a “Triple X”. i.e. A diamond which has been given an Excellent, Excellent, Excellent cut grade and that  given a Very Good Very Good Very Good is imperceivable to the every day layman and in most cases imperceivable to the laboratory grader face up. This is causing huge debate currently in the gemological circles as battles reign on the beauty of diamonds cut over 100 years ago, many of which would receive a “fair” or “Good” cut grade versus modern stones. What one person deems as beautiful versus what another person deems as beautiful could be poles apart. Having said all that there are some unpleasant things to stay away from with regards to a diamonds symmetry. These are as follows :

1. The Fish Eye and the Nail Head 

Note on the image on the left the reflection of the girdle is visible through the table facet. Not a nice thing to see through the stone. The image on the right is a very deep stone so all the light is lost through the pavilion or bottom of the diamond

Fish Eye


2. Diamond Weight versus symmetry 

Weight Diameter

3: Girdle Thickness 

Girdle thickness




proportionscut grade

Images Courtesy of the GIA