What is the Significance of Diamond Polishing

Diamond polishing as a quality factor might sound curious to some. After all, when it comes to measuring diamond quality the four main factors that determine its beauty and value are based on the famous 4Cs of diamonds. The GIA (Gemological Institute of America) standard has stood the test of time in measuring diamond quality.

But as it happens there is another important measure when it comes to assessing diamond quality, which has been developed and advanced by the GIA. One that is carefully followed by top diamond cutters in the industry. Enter Diamond polish. Which is the subject of this Education page.

Note that in outlining the importance of diamond polishing and how it affects diamond value, we will not be engaging in the actual process of how diamonds are polished. That is a subject for another time.

Preconditions for Diamond Polishing

The subject of diamond polishing might seem quite straightforward at first glance. For the general observer, it would take to mean a diamond: which is a hardened carbon stone that has been polished. And to be fair this view is not too far from the truth.

However, when it comes to diamonds and precious stones, and generally anything concerning fine jewellery, things are usually not as simple. When it comes to diamond polishing the first point we need to consider is that when it comes to the topic of diamond polishing we are only talking about cut diamonds. A subject that must be engaged prior to moving towards the main point of polishing. 

When it comes to diamond polishing diamonds in their rough form are not considered. Even if the diamonds in question have been shaped in a particular fashion: such as in cabochon stones: which only involves the outward shaping of the stone followed by polishing, and is not as popular in the diamond world. Nor does diamond polishing strongly feature in more exotic diamond “cuts
like the rose cut, which only contains minimal faceting (3 - 24).

So the subject of diamond polish mainly involves cut diamonds which feature a number of facets that are cut symmetrically per standards. So when it comes to diamond polish we almost always only consider the recognised diamond cuts: princess, cushion, oval, etc.

What is Diamond Polish?

Right. So with that subject behind us, we can now move to the question of what is meant by diamond polish. Basically, the polishing of a diamond is a process the gemstone is subjected to, enabling and enhancing the stone’s natural brilliance, fire, and scintillation which are determined by its cut and faceting. In other words, the polishing of the diamond is a natural step that follows the others.

The reason for this is that the polishing of the diamond aims to enhance the smoothness and shine of each individual facet of a diamond. And the facets of the diamonds as you may know emerge as a result of the faceting and cutting process. And the quality of the faceting in turn will determine how well light passes through it.

When it comes to the actual process of polishing, usually diamonds are polished by a variety of instruments that will vary depending on the technology the company in question is adopting. However, the fundamentals of the process remain the same. The aim of polishing is to refine the surface of the stone when it comes to each individual facet. In this process, the extremely minor surface blemishes that exist on the stone that have escaped or may have resulted from cutting and facetting of the stone, and hence obstruct the reflection and refraction of light are smoothed out.

Diamonds are usually polished using diamond dust and other agents with varying levels of abrasion to smooth the surface of the stone. However, this comes at a cost, as a certain percentage of the diamond will be smoothed off. The polishing of the diamond can be carried out by polishing wheel as used in primitive times. To more advanced rotating discs which are powered by motors and can polish the stone at immense speeds.

The Relationship between Diamond Polish and Symmetry

The relationship between diamond polishing and symmetry can be understood by following the process by which rough diamonds that are sourced from nature or grown in a lab become the gem quality that they are.

You see, diamonds in their rough state whilst extremely durable and with a degree of glow are not like the stones that you and I associate with. In their rough form diamonds appear oily with a dull or dim look to them. The process of diamond cutting and polishing is to help give the stones their distinct visual character.

The cutting of the stone is a complex process that today involves computerised cutting tools and other hand-crafting equipment. Following this step, the diamond is surveyed by an expert gemologist, who would provide some kind of rating for the stone, notably on its internal clarity before sending it to the next stage. Which is the faceting of the stone.

The faceting stage is where the diamond takes on a distinct look: in terms of the type of faceting such as brilliant, step, or emerald. Followed by the overall shape: round, cushion, and oval. Now it is at this stage that the polishing of the diamond becomes key. For when it comes to the faceting of the stone (such as 58 or 57 facets found in round brilliant cut diamonds), these facets have an effect on the quality of the stone and in turn, impact the quality of the polishing.

GIA’s Diamond Polish Grades

Whilst not as well recognised as the 4Cs, diamond polishing also follows a set grade that as noted is set by the GIA. These grades exist as general guidelines for those who wish to learn more about the quality of their cut, polished diamond.

  • Excellent: A diamond with no flaws resulting from the polishing process, even when viewed under 10x magnification, is rated as such. Naturally, they are the best in the business.

  • Very Good: The second on the list, these diamonds feature no visible flaws related to polishing, but certain flaws can be spotted when viewed under 10x magnification.

  • Good: Flaws in these diamonds are visible, but only under close inspection to the naked eye. 10x magnification will reveal certain flaws more clearly.

  • Fair: Features visible flaws to the naked eye, bu not too significant to affect the overall quality of the stone. But 10x magnification will reveal a different story.

  • Poor: Poorly polished diamonds feature flaws that are visible both under magnification and when viewed with the naked eye. They are a bad choice.

Importance of Polishing on the Value of Diamonds

This is an interesting point and the answer to the question of the relationship whilst seemingly obvious is not always straightforward. When it comes to diamond value the key factors are always the 4Cs. And it is best to ensure that the diamond of your choice matches up with regard to the standards that are set when it comes to the stone’s color, clarity, carat, and especially the cut.

The cut of the diamonds all aspects of the stone, and its quality is greatly dependent on the original clarity of the stone. These are important considerations, since clarity in addition to exerting a direct effect on the core qualities of the diamond: its brilliance, scintillation, and fire. It also relates to the kind of polishing the diamond will be subjected to. Since much of the polishing process is about minimising the surface-level shortfalls that the diamond naturally has.

Hence when opting for a top-quality diamond with high-grade polish, one is better simply opting for a diamond that scores well in the 4Cs, with the higher polish grade a secondary but important add-on. Critical again is the cut of the stone. As mentioned the symmetry of the diamond, which is a function of the cut, has a great effect on the final polish of the diamond.