Princess cut is one of the most sought-after diamond cuts, second only to the classic round cut in popularity. Princess cut diamonds have a square shape when looked at from above and are a good choice for engagement or wedding rings.
Let’s take a look at the most important facts you should know when shopping for princess cut diamonds.
Price of Princess Cut Diamonds
Princess cut diamonds are generally cheaper per carat compared with their round cut counterparts.
The main reason for this is that when raw diamond is shaped into a princess cut, less material is wasted than when cutting a round stone.
Evaluating Princess Cut Quality Characteristics
When it comes to assessing cut quality, there is no uniform agreement as to what proportions the best princess cut should have.
Even if the diamond you buy is certified by the G.I.A. (Gemological Institute of America), its cut won’t be assigned an overall quality grade in the grading report (unlike the round cut). You will only be able to see a grade for the diamond’s polish and symmetry, which should have a grade of at least Good.
Generally, the best cut will maximize the stone’s brilliance, without making the diamond look too deep or too shallow.
The rule of thumb for princess cut diamonds is to look for stones whose total depth (or height) is about 70% of their width (5 percentage points should be an acceptable deviation from this number, up or down).
When looked at from the top, the diamond should look square (stones that look rectangular are usually cheaper).
The most important specifications on which a princess cut is evaluated are its girdle, length-to-width ratio, depth and table percentages, and the presence of a culet as well as its size.
Let’s take a more detailed look at these quality characteristics:
The girdle of a diamond is its widest part.
This outer edge can have a thickness grade that ranges from Extremely Thin to Extremely Thick.
For princess-cut diamonds, the optimum girdle thickness ranges from Very Thin to Thick.
Diamonds with Very Thick girdles are undesirable because their other proportions are distorted due to the overly large girdle.
Extremely Thin girdles are also to be avoided because they are vulnerable to chipping.
The thickness of a princess-cut diamond’s girdle is measured vertically, so you will simply need to determine its height.
Length-to-Width Ratio for Princess Cut
The length-to-width ratio of a princess-cut diamond tells you how close its shape is to square. The length and width of a princess cut are measured along the girdle.
Usually, the length-to-width ratio in princess cuts is around 1-1.1. Values closer to 1 are more desirable for this type of cut, whereas ratios above 1.1 are less sought after.
Depth Percentage for Princess Cut
The depth of a princess-cut diamond is the distance from its table to the bottom of the stone.
The depth percentage of a princess-cut diamond is calculated by dividing the depth of the stone by its width.
It is best if this value is between 65% and 75%. Values in the 58%-64% and 75%-80% ranges are also considered good.
Princess cuts with depth percentage values below 58% and above 80% are considered fair or poor quality.
Table Percentage for Princess Cut
The table of a princess cut is the rectangular flat facet on the top of the stone. (The width of the table is less than the width of the entire diamond.)
The table percentage is calculated by dividing the width of the the table by the width of the stone as measured along the girdle.
A table percentage of 60%-75% is considered best for a princess cut. Diamonds with tables in the 75-80% or 56%-60% range are also considered well cut.
In general, avoid princess cuts whose table percentage is higher than 85% or lower than 55%.
The culet is the small flat facet on the bottom of a diamond. Often, the culet is missing, and the bottom is simply a pointed end.
It is best if the culet is small or if there is no culet at all. (Some people prefer to have a culet because they think sharp diamond bottoms are more likely to chip.)
Medium to large culets are undesirable because they are too visible when the stone is looked at from the top and spoil the appearance of the table’s light pattern.
One of the good things about princess cut is that its proportions allow it to exhibit a decent amount of brilliance and sparkle, which make the stone’s inclusions less visible.
(Round diamonds rank highest in this respect, whereas most other shapes are less sparkling.)
It is worth noting that princess cut diamonds with clarity lower than SI1 are rare.
That’s why the best way to find a stone with decent clarity at the lowest price is to focus on stones graded VS1, VS2 and SI1. When looking at diamonds in this clarity range, look for stones that don’t have inclusions visible with the naked eye.
There is one other thing you should pay attention to: Make sure that the stone you choose doesn’t have serious inclusions in its corners, which are the weak spots of this cut. If there are large inclusions in these places, the corners will be weakened even further and be more prone to chipping.
When evaluating the color of a princess cut diamond, look for stones that don’t have a visible yellow tint. This means that you shouldn’t go lower than the Near Colorless range (which contains the G, H, I and J grades).
Although with round cut stones you have more leeway in terms of color (i.e., stones graded J or even K can still look reasonably colorless because the cut masks tints well), with princess cut diamonds you shouldn’t go lower than the I-color grade or you will start seeing some yellow.
Should you go even higher and buy a Colorless princess cut stone (i.e., one graded D, E or F)? It is up to you, but it is usually not worth the additional money you’ll pay as you won’t be able to see a noticeable difference in color with the naked eye.
Selecting a Setting for a Princess Cut Diamond
When buying a princess cut diamond, you should make sure that it is set in a mounting that protects the stone’s corners. Since this is where the diamond gets very thin, if the corners are not well protected, a strong blow can chip them.
A V-prong setting, for example, is a great choice for keeping a princess cut stone safe.
A note on diamond accents: If your princess cut diamond is going to be set together with other stones, make sure that the accent diamonds are the same color as the center stone or no more than one grade apart.