How to Buy an Engagement Ring? - Part 3: What is Diamond Cut?
Step 4: Understanding the 4 C's
In your journey to buy a diamond, you might have come across the term "4 C's." In 1930's, Robert M. Shipley established the Gemological Institute of America (GIA). His goal was to train jewelers in gemology. He also developed a standard to measure the quality of diamonds. The 4 C's are:
What is diamond cut?
In my opinion, cut is the most important trait in a diamond. It relates to brilliance, which I mentioned in Part 2. Generally speaking, the better the cut grade, the better the aesthetic value of the stone. A Belgian mathematician analyzed optic physics of a diamond to create the modern round brilliant cut. This pattern produces the most light return/brilliance possible. The proportions of the round brilliant are also the standards to which we grade cut for diamonds.
Diamond graders analyze cut by estimating the facet proportions, angles, polish, and symmetry. Gemologist assign cut a grade (Excellent (EX), Very Good (VG), Good (G), Fair (F), or Poor(P)) based on the aggregated results of the analysis. While diamond buying, you might have heard the term "triple x" ("x" or "ex" refers to Excellent grade). It is being used to describe cut, polish, and symmetry. These properties typically identify a very well cut diamond. I say typically because you should never buy a diamond without seeing it first.
One thing to note: Fancy shape diamonds (any shape not round) are usually not given a cut grade because the shape and dimensions are not standardized like rounds. They are still graded on polish and symmetry. It is tough to evaluate a fancy shape diamond based on the certificate alone. I would recommend you see it in person alongside other diamonds of the same shape.
My Opinion on What is Diamond Cut
Unless you're a diamond grader evaluating a stone face up, these properties aren't very noticeable. Most people like to go for Very Good to Excellent rating. My personal opinion is to go for “triple x” because they are better at retaining their value over time. I would never buy a round shaped diamond with a cut that was anything below Very Good.