Diamond cuts are aimed at modifying and enhancing the looks of diamond crystals. There are many types of diamond cuts, like brilliant, rose, step, mixed, etc. The most popular among them is the round brilliant cut, followed by the princess cut. A princess cut diamond has a square or rectangular shape, with four pointed corners. The brilliance of a princess cut diamond is only slightly lesser than that of a round brilliant cut. So it is also known as 'square modified brilliant'. Nevertheless, princess cut diamonds are different and unique in their shape and facet arrangement. Developed during the 1980s, the princess cut has the best features of both round and square cut diamonds. These diamonds display the same degree of light return as that of a brilliant cut.
Princess cut is equally popular among diamond cutters, as these diamonds retain more crystal weight. According to them, princess cut diamonds retain a major part of the rough diamond, as compared to the round brilliant cut. Almost 80% of the rough diamond is retained in case of a princess cut; whereas, only 50% is retained in a round brilliant cut. So princess cut diamonds are cheaper, when compared to round brilliant cut diamonds. Rough diamonds that come in the shape of octahedron crystals (like two pyramids joined at the base) are used for making princess cut diamonds. In case of other diamond cuts, only a single diamond is made from a rough diamond, whereas two princess cut diamonds can be obtained from one rough diamond. This again means very less wastage of the original rough stone.
Princess cut diamonds are square or rectangular, with four sharp and uncut corners. Such a diamond looks like an inverted pyramid. In this type of diamond cut, the facets in both the crown and the pavilion are arranged in a vertical fashion, which is in contrast to the facet arrangement in other cuts. The length-to-width ratio of such a diamond can determine its dimension. If the length-to-width ratio is anywhere between 1 and 1.05, the diamond will appear as a square, and the rectangular ones have a ratio of more than 1.10. Most of the princess cut diamonds have 50 or 58 facets. In the former, 21 facets are in the crown or the top portion, 25 are in the bottom part called pavilion, and 4 are in the middle part called the girdle; whereas the latter has 21 in the crown, 4 in the girdle and 33 in the pavilion. You may also come across princess cut diamonds with around 76 facets.
The rate of light return in princess cut diamonds is more than that of the ordinary square cut diamonds, as they have tent-like facets and vertically angled crown. It is always better to avoid those diamonds which have very large facets and shallow crown heights. These diamonds are graded for light return by Accredited Gem Appraisers (AGA), American Gem Society Laboratory (AGSL) and European Gem Laboratories - USA (EGL-USA). According to AGSL a cut grade of '0' is considered the highest grade and as per the AGA and the EGL, 'EX' is the highest grade.