Round Brilliant Cut
The Round Brilliant cut diamond is the most popular of all the diamond types. This is for two very good reasons. Firstly, it is the most versatile of all diamond shapes, and can be set into many many differing designs, because it has no corners around the girdle (outer edge). Therefore, there are very few restrictions on where the diamond can be held in place. Jewellers and ring designers then have many more options when it comes to claw placement and setting construction.
The second reason is that from a technical perspective, the round brilliant cut diamond is the best shape cut to maximise the brilliance of the diamond crystal. The best of the round brilliant cuts are given a grading of “Excellent” (in GIA certificates) or “Ideal” (by the AGS).
This “Excellent” cut is a term that the GIA specifically uses to describe a diamond that has been cut to and conforms with the GIA’s highest recommendation for optimizing the refractive qualities of the diamond whilst retaining the maximum physical diameter, without compromising the cut.
The GIA has some tolerance in the grades for the diamond to fall within, so not all “Excellent” cut diamonds will be exactly the same in every respect. However, all must meet the very tight parameters of the minimum cut grading system in the Excellent cut standard.
Mathematically perfect diamonds in the round brilliant cut are in fact seldom created, as cutters would need to cut the diamond’s outer edge, called the “girdle”, down to a zero thickness. This, of course, would be susceptible to damage. Cutters will normally give a well cut diamond a girdle that is around 3 % thick, that is to say it is equivalent to 3 % of the diamond’s total depth.
The round brilliant cut is the most exacting of all cuts when cut to the highest levels. However, just because a diamond is round in shape does not mean that it is a good diamond. Many, many poorly cut round brilliant diamond are out there and are sold by some suppliers.
The very best of the Excellent cut grade diamonds will show a hearts and arrows pattern, particularly when viewed with a hearts and arrows scope. When you look at a well cut round brilliant cut diamond, you can see the arrows if you look closely at the top of the diamond. The arrow effect is visible in many of the rings on this site, for example in the banner section at the top of each ellissi page, in the cluster ring at the center, you can see the 8 pointed star with its arrows pointing outward. The hearts effect is viewed from the back of the diamond through the hearts and arrows scope. The scope reveals the alignment of facets that is an illusion created from reflections within the diamond. However, this only occurs if the diamond is of the highest cut standards.