Princess Cut Diamonds

intablogdiamonds, education, Engagement Rings


What is a Princess Cut?
When I first joined the diamond and jewelry industry, my favorite diamond cut was the princess cut. I liked the princess for its modern edgy style. Princess cut diamonds have a brilliant-style shape and are considered contemporary due to their sharp, pointed, uncut corners. Princess cut diamonds are generally cut in the shape of a square or rectangle. In 1980 the first princess cut diamond was developed by Betzalel Amber and Israel Itzkowitz of Ambar Company in Los Angeles. At the time, the newly invented princess cut was considered to be avant garde because of its unusual shape, but today it is currently one of the most popular diamond shapes around.

As indicated by the plotting diagram of the facet structure above, the crown and pavilion facets are structured vertically, instead of being structured horizontally as is typical of older step-cut diamonds such as the emerald cut.

Square Ratios
At INTA, we prefer princess cut diamonds that are shaped to as near a perfect square as possible. Perfect square diamonds have a length-to-width ratio of 1.00:1.00. It is determined by dividing the average length by the width. For instance a one carat princess cut diamond of ideal proportions might have a length of 5.35 mm and a width of 5.36 mm. Although the measurement is slightly off by .01 mm, it would still be expressed as having a length-to-width ratio of 1.00:1.00. However, there are also princess diamonds that could be cut slightly elongated. An example is a princess diamond with a length measurement of 5.47 mm and a width of 5.32 mm. The length-to-width ratio on that particular measurement would be 1.03:1.00. Although the ratio is slightly off, it is still considered a pretty square diamond, but is less desirable than a near perfect square.

What Makes Princess Cuts Lower Priced than Round Brilliant Cuts
Princess cut diamonds tend to be a little lower in price than a round brilliant cut diamond because it has better weight retention. In fact, cutting a princess generally results in a yield of 65% of the weight of the rough crystal. Whereas the average yield for a round brilliant cut diamond is closer to 50%. A rough crystal used to produce diamonds originally comes in an eight-sided shape known as the octahedron. When a princess is cut, the octahedron rough crystal can be sawn in half, yielding two princess diamonds. The portion of the sawn surfaces becomes the tables of the two princess diamonds. Therefore, the combination of these factors contribute to the fact that princess cut diamonds usually cost less than round brilliant cut diamonds of comparable carat weight, color and clarity.

Even though princess cut diamonds tend to cost less than round brilliant ideal cut diamonds of comparable quality and size, the princess cut diamond tends to appear smaller when viewed face up because princess cut diamonds are cut deeper. For instance, the average one carat round brilliant cut diamond will measure 6.50 mm in diameter, while the average princess cut diamond of the same weight will measure somewhere in the range of 5.30 – 5.40 mm in diameter. In order to get a princess cut diamond of the same diameter measurement (when measured from side to side) of a one carat round, one would have to purchase a princess cut diamond weighing closer to 1.70 – 1.80 carats. However, one might be able to get away with comparing the size of a princess cut diamond to a round with a tip-to-tip measurement, in which case the princess will always sound like a larger stone.

The Magic Numbers (Proportions)
Since round brilliant cut diamonds tend to have “magic numbers” that are comprised of the stone’s ideal measurements, proportions, percentages, facets, etc. People often ask us what the “magic numbers” are for princess cut diamonds and as surprising as it may be, there is no magic set of numbers that will assist you in selecting a princess cut diamond. We select our princess cut diamonds based on the optical symmetry of the diamond, because visual performance (brilliance, dispersion, scintillation) go hand-in-hand with optical symmetry. You’re probably wondering what the optical symmetry within a diamond is. Optical symmetry refers to the visible symmetry of the facets within the diamond (section by section). The degree to which the sections of facets within the diamond are symmetrical and evenly spaced will have a direct impact on the visual performance (brilliance, dispersion, and scintillation) of the diamond.

In GIA grading reports the princess cut is referred to as a square or rectangular modified brilliant. It may have range of either 50 facets (21 located on the crown, 4 on the girdle, and 25 on the pavilion) or 58 facets (21 on the crown, 4 on the girdle, and 33 on the pavilion), depending on how the pavilion is cut. This cut is usually a square shape where the length-to-width ratio is 1.05 or less.

Princess cuts basically resemble an upside-down pyramid that contains most of the carat weight in the pavilion (lower) and as I mentioned earlier tend to be one of the smallest of the shapes for the same carat weight. Princess cut diamonds with larger total depth percentages are much smaller in length and width than lower depth stones.


Flaws such as naturals, inclusions, and extra facets are usually found at the corners of the princess cut because the corners are located on the outer edges of the original rough diamond crystal. Since the corners of a princess cut are usually covered by a V-shaped prong (image above), irregularities at the corners are often not visible once set. However, these same irregularities can also lead to durability problems. The sharp, squared-off corners of the princess cut require great care when setting and need to be protected to avoid chipping or cracking.

Princess Cut Buying Tips
Princess cut diamonds are perfect for channel or invisibly set diamond jewelry. They also make a great alternative to the traditional round diamond because they are lower in price. At INTA Gems, we recommend that:

1. Princess cut diamonds should have a depth and table of 60-70%, with smaller depth and table percentages preferred. Keep in mind that deeper princess cuts are very small in length and width for the same carat weight.

2. Pick princess cut diamonds that contain lots of brilliance. Therefore, choose ones with “Very Good” to “Excellent” polish and symmetry grades.

3. In terms of color and clarity, we recommend at least H color and SI1 clarity.

4. When picking a prong setting for a princess cut, always pick four prongs to protect the four pointed corners on a princess. For better protection of the corners, pick V-prong settings.

What to Avoid
1. Polish and symmetry grades that are below “Good” because the diamond begins to lose it’s brilliance and sparkle.

2. Avoid extremely thin or extremely thick girdles because it makes the diamond more prone to chipping.

3. Another thing to avoid is the bowtie pattern (that is sometimes found in fancy cuts) because it leaves a dark shadow in the center.

4. Lastly, do not purchase princess cuts that are cut too deep or shallow because it affects the overall appearance of the stone as reflective light escapes from the bottom.

For these various reasons, I really love princess cut diamonds. In fact, the love for princess cut diamonds run in my family. My cousin (Steve’s wife) got a 1.52 carat princess cut diamond center that is accompanied with eternity round brilliant cut diamonds in a platinum setting. She absolutely loves her ring! Our company even named that particular eternity diamond setting and princess cut diamond combination the “Anna Ring.” For more information on princess cut diamonds, come down to our store. We look forward to seeing you! Also try other reputable companies such as Cartier and De Beers.