Cut, Polish & Symmetry of Diamonds

When buying engagement rings, most people do some research beforehand and read up about the 4 C’s of diamonds-cut, colour, clarity and carat weight. However, there is more to diamonds than just that. The polish and symmetry also plays and important role in maximising your diamond’s sparkle.

Many will group cut, polish and symmetry in together when talking about diamonds. For instance, a triple X ring is one in which the cut, polish and symmetry of a diamond are all graded excellent. The possible grades are- Excellent, Very Good, Good, Fair and Poor.


The cut is perhaps the most important of these factors. There are 3 factors to consider when it comes to cut- fire, brilliance and scintillation.  These all depend on the quality of the cut of the diamond. All these factors relate to how well the diamond interacts with light- internal and external white light reflection, how well it reflects the spectrum colours visibly and the overall sparkle.


This refers to how the individual facets in a diamond are intersecting and aligned. A higher grade of symmetry gives the diamond a higher brilliance. A diamond with poor symmetry means the diamond reflects light incorrectly and redirects it at odd angles. However, it is very difficult to tell the difference between a Good symmetry and an Excellent one. Symmetry matters more for diamonds of a higher clarity, VVS2 and above so it is not something to worry too much about as it is very difficult to differentiate.


A diamond’s polish relates to how smooth the facets are in a diamond. A rougher polish may obstruct light and change the light patterns.  A poorly polished diamond may have smudges or appear more gritty. In most cases, polishing defects would not be visible by the naked eye, it would only be under intense magnification that it would become apparent. As a loose rule, for any carat weight below .75ct, a polish grade of Fair and above is appropriate as no polish issues could be seen by the naked eye.


Here at Commins and Co, we are committed to delivering the highest quality diamond to suit your budget and taste.

See here for more advice for buying diamonds and engagement rings.