What Is A Princess Cut Diamond?

Princess cut diamonds are sometimes known as "square cut diamonds" for obvious reasons: they offer a beautiful square cut diamond shape that is both elegant and unique among the other diamond cuts. While princess cuts make up only 5.3% of all diamonds on the market (based on current inventory figures), they are actually the second most popular diamond shape - beating out cushion (5.2%) and oval (3.8%).

One of the major advantages of choosing a princess cut, beyond it's sophisticated aesthetic, is the princes cuts slightly lower price point. Princess cut diamonds are considerably less expensive than their more popular sister the round cut (which makes up 75% of diamond inventory).

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Square Cut vs. Rectangular Cut Diamonds

The main focus when choosing a princess is typically the length-to-width ratio (often called LTW), which should be as close to 1 as possible and no more than 1.05 for a classic square cut princess. Some people prefer rectangular princess cut diamonds like the one above, but rectangular cut does not tend to be as popular as the square cut princess.

1 carat square princess cut diamond with a length-to-width ratio of 1.00 1 carat rectangular princess cut diamond with a length-to-width ratio of 1.15

The length to width ratios of these two diamonds are 1.00 for the square princess cut and 1.15 for the rectangular princess cut.

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Princess Cut Diamond Color Grades

Color grade is the indication of how white or yellow (or brown, green, etc.) a diamond appears to the naked eye. Color is highly subjective and generally speaking, most people cannot tell the difference between near colorless diamonds (graded G - J) and colorless diamonds (D - E) unless they are being shown right next to one another (and even then it can be difficult to tell the difference).

When it comes to princess cut diamonds, we generally recommend that you begin by looking for an I or better color grade if you're choosing a platinum setting and a K or better color grade if you're choosing a yellow or rose gold setting. That said, the carat weight of the diamond can haveIf you are going for a very larger carat size (say 2 carat or more) you may also want to consider better color grades.

However, there are a lot of great examples of larger princess cut diamonds where an I color looks nice and white in a platinum setting.

Check out the below diamonds, can you tell the difference in color between an H (5th diamond) and a D color diamond (1st diamond)?

2.5 carat D color princess cut diamond 2.5 carat E color princess cut diamond 2.5 carat F color princess cut diamond 2.5 carat G color princess cut diamond 2.5 carat H color princess cut diamond 2.5 carat I color princess cut diamond 2.5 carat J color princess cut diamond 2.5 carat K color princess cut diamond

Prices from top left to bottom right: $29,009 2.5 carat D color VS2 clarity, $33,950 2.5 carat E color VS2 clarity, $20,793 2.5 carat F color SI1 clarity, $25,463 2.5 carat G color VS1 clarity, $22,669 2.52 carat H color VS2 clarity, $16,359 2.51 carat I color VS1 clarity, $14,140 2.52 carat J color VS1 clarity, $10,590 2.35 carat K color SI1 clarity.

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Princess Cut Diamond Clarity Recommendations

Clarity is the toughest aspect of a diamond to judge simply based on a diamond’s grading certificate alone. Two diamonds with the exact same size and clarity grade on paper can look totally different depending on the types of inclusions and where they are located inside the diamond.

Generally speaking, the differences in appearance are not relevant in the better clarity grades like FL, IF, VVS1, VVS2, VS1, and even VS2 clarity – though occasionally a VS2 clarity will not be totally eye clean depending on the size and location of its inclusions as well as the carat weight of the stone. On the flip side, SI1 diamonds can appear totally eye clean when they have inclusions in a certain location where it is less visible, despite being graded as worse than VS2.

Eye clean means that a diamond looks flawless without the aid of magnification from a jewelers loupe or microscopic lens. As you can see the above is an example of a 1.21 carat I color SI2 clarity diamond that won't be eye clean (click to see a 360 degree video that shows the black speckled inclusion even more).

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Princess Cut Diamond Prices

Princess is among the most popular diamond shapes, but still commands a significantly lower price point than round diamonds. Below is a chart depicting the price (y-axis) trend for a large population of H VS2 princess cut diamonds (GIA certified very good or better polish & symmetry). The price trend was solved using a simple regression on a the data set – our pricing algorithms use a more sophisticated machine learning algorithm than this model and incorporates several additional factors including each diamond’s specific dimensions. However, for studying simple price trend the below will paint a simpler picture. As you can see, a 1 carat H VS2 princess diamond costs approximately $4,300 while a 2 carat costs approximately $15,500. This exponential growth in price (the price more than doubled when the size doubled) is due to the diamond pricing metric that most jewelers cite when discussing value: price per carat. Every diamond shape exhibits a similar exponential price trend as carat size grows larger. This is summed up by saying, “the price per carat increases as the carat size increases”.

Ideal Dimensions, Proportions, and Angles for a Princess Cut Diamond

Generally speaking, most jewelers recommend you focus on finding a table between 65% - 75%, depth between 66% - 75%, with very good polish/symmetry.

StoneAlgo always recommends you consider GIA Very Good or Excellent polish and symmetry grades for princess cut diamonds to ensure your diamond looks its best - but what about cut? The GIA does not currently grade the cut quality of fancy shapes like they do for round cut diamonds. Instead, as buyers we have to focus on some rules of thumb and, most importantly, visual appearance.

Princess cut diamonds aren't graded on cut by the GIA like round diamonds are, but the AGS does score the light performance of princess cuts and we recommend you check out some of Brian Gavin's amazing princess cuts if you want to see examples of high cut quality in a princess. Below are some general ranges StoneAlgo recommends for Princess.

  • Ideal Table Percentage: 65% - 72%
  • Ideal Depth Percentage: 66% - 75%
  • Ideal Girdle Thickness: Very Thin - Slightly Thick
  • Crown Height: 10% - 16%
  • Culet: None

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Princess Cut Diamond Fluorescence Recommendations

Diamond fluorescence produces a glowing property in some diamonds when they are exposed to ultraviolet light. To give an example of how prevalent fluorescence is in the diamond market, this affect is present in about 35% of the diamond inventory available at Blue Nile currently. Fluorescence is not necessarily a good thing or a bad thing, but like most things in life it’s good in moderation or in certain situations. For example, if you are buying a colorless diamond (D – E), then fluorescence may not be a good thing. But for diamonds grade I – K and lower, faint or even medium fluorescence can actually help the diamond appear whiter. Strong fluorescence is typically not recommended as it can make the diamond look hazy – so we’d recommend you stick with faint or none to be safe. You may have seen the designation negligible fluorescence which is the AGS grading equivalent to the GIA’s “none” qualification – representing diamonds that do not exhibit fluorescent properties.

Protect Your Princess Cut's Corners

One of the defining features of a princess cut diamond is its beautiful, square-cut corners. However, these delicate corners are both a blessing and a curse as they make the princess cut diamond more fragile than most other cuts. While you may be familiar with the diamond’s legendary status as “the hardest element on earth”, this is only true to a point. It really means that a diamond cannot be scratched by another element – it doesn’t mean that if you smash a diamond with a hammer it won’t shatter or break (it can and will). Placing protective prongs on each corner will help mitigate this risk and protect a princess cut diamond’s corners from harm.

Drop us a Line if you need further assistance!

That concludes our general recommendations for cushion cut diamonds. There are a lot of moving parts but generally speaking we try to maximize carat size for our given budget by sticking to the lower end of the color ranges we specified and searching for VS2 or better diamonds. SI1 diamonds are great if they’re eye clean, but they are a pain to find and often end up costing just as much as a VS2 diamond would. If you need one-on-one advice, we offer free support to all our users – simply drop us a line at management@stonealgo.com

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