Depth, width, roundness, and uniformity of facets determines the brilliance of a diamond. Of the 4 C’s, the cut of a diamond is the only one that we can actually control. A rough stone in the hands of a skilled craftsman can be transformed into a gem of true beauty.

How the cut influences the brilliance of a diamond

As light enters a diamond, it reflects off its many facets. This gives a diamond its brilliance and sparkle. The angles of the facets – in relation to the other facets on the top and bottom of a diamond – initially determine the quality of the cut. In addition, the top and bottom portions of the diamond must have the correct proportions in relation to each other. A stone that is cut too deep (or too shallow) will lose much of its brilliance, as shown in the diagram below. Finally, a well cut diamond will have a table, the flat upper surface of the diamond, with the correct size in relation to the overall size of the stone.

What does this mean? A well cut diamond will maximize the amount of light that reflects out of it. A poorly cut diamond allows the light to escape out its bottom and sides, reducing the overall brilliance of the diamond.