Many people confuse diamond cut with the shape of a diamond. Unlike shape, diamond cut is the metric used to evaluate the precision and quality of the overall cutting itself. Diamond cut is the most complex of the 4 C’s, and not even the major labs agree on how to best measure the quality of a diamond’s cut.

1. When a diamond is cut to good proportions, light is reflected from one facet to another and then dispersed through the top of the stone.
2. If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion.
3. If the cut is too shallow, light escapes through the pavilion before it can be reflected.

Up until several years ago, evaluating the cut of a diamond was not an easy task. Dimensions, proportions of the diamond and it’s finish (both symmetry and polish) were al information we had to go buy making it difficult for consumers to understand what’s a well cut diamond and what is not. Symmetry measures how well the facets match the other facets. A diamond cut with very good or excellent symmetry may be perfectly calibrated with all facets matching perfectly but still cut to poor dimensions. A diamond polished perfectly may have excellent surface finish but also be cut to poor dimensions. So while symmetry and polish help you determine if the diamond is cut well, it doesn’t always mean the diamond will perform like a well cut diamond.

Recently both the GIA and AGS have adopted “Cut Grades” which factor all these things together; the proportions, symmetry and polish, and sometimes even light performance. Currently, GIA issues a cut grade on its round diamonds, and AGS issues a cut grade on round and princess shape diamonds they grade.

So what's the best cut diamond? How do I know my diamond will sparkle well? Ask our diamond experts and get free advice in our forum! > ENTER FORUM