Princess Diamond
The princess cut is a square modified brilliant with sharp, uncut corners that deliver exceptional brilliance in a geometric silhouette. It's the most popular non-round shape and offers outstanding value, costing significantly less per carat than rounds.
Overview
The princess cut was developed in the 1960s and 1970s, with the modern version typically attributed to Betzalel Ambar and Israel Itzkowitz in 1980. Its appeal lies in combining the brilliance of a round brilliant (thanks to its modified brilliant faceting pattern) with the clean, geometric lines of a square shape. The result is a diamond that sparkles intensely while offering a distinctly contemporary aesthetic.
From a rough utilization standpoint, the princess cut is one of the most efficient shapes, retaining up to 80% of the original rough crystal. This is because the square shape closely mirrors the octahedral crystal structure of diamond rough, minimizing waste. This efficiency translates directly to lower prices—princess cuts typically cost 25-35% less than round brilliants of comparable quality. Two princess cuts can often be produced from a single octahedral crystal, further improving yield.
The most important consideration unique to princess cuts is corner protection. The four sharp, 90-degree corners are the thinnest parts of the stone and are vulnerable to chipping on impact. Every princess cut must be set with corner-protecting prongs or a channel/bezel setting. In the trade, princess cuts with chipped corners are a common repair issue, and jewelers should always counsel clients about this risk. Despite this drawback, the princess cut's combination of brilliance, modern geometry, and exceptional value keeps it firmly as the number-one alternative to the round brilliant.
Carat to Millimeter Chart
Approximate face-up dimensions for princess diamonds at each carat weight.
| Carat Weight | Size (mm) |
|---|---|
| 0.25 ct | 3.3 x 3.3 |
| 0.5 ct | 4.2 x 4.2 |
| 0.75 ct | 4.9 x 4.9 |
| 1 ct | 5.5 x 5.5 |
| 1.25 ct | 5.9 x 5.9 |
| 1.5 ct | 6.3 x 6.3 |
| 2 ct | 7.0 x 7.0 |
| 3 ct | 7.9 x 7.9 |
| 4 ct | 8.7 x 8.7 |
| 5 ct | 9.3 x 9.3 |
Pros & Cons
Advantages
- +Exceptional brilliance—rivals round brilliants in light performance
- +25-35% less expensive than comparable rounds
- +Clean, modern geometric lines that appeal to contemporary tastes
- +Most efficient shape for cutting from rough—excellent value
- +Works beautifully in channel-set bands where stones sit flush together
- +Strong brilliance hides inclusions well, allowing lower clarity grades
Disadvantages
- -Sharp corners are highly vulnerable to chipping—must be protected by the setting
- -Corners with chips or damage significantly reduce value and structural integrity
- -Tends to show color more than rounds—consider higher color grades
- -Square shape can appear smaller face-up than elongated shapes of equal weight
- -No standardized cut grade from GIA—need to evaluate proportions independently
- -Finding well-matched pairs (for earrings or side stones) can be challenging
Buying Tips
- •Corner protection is non-negotiable—always choose a setting with V-prongs or bezel at the corners
- •Look for stones with chevron facets visible through the table—this indicates proper brilliant-style cutting
- •Keep L/W ratio between 1.00 and 1.05 for a true square appearance; anything over 1.10 will look rectangular
- •Princess cuts can tolerate SI1-SI2 clarity better than step cuts because the brilliant faceting hides inclusions
- •Color tends to concentrate in corners—stay at H or above in white metals
- •Check the depth percentage: 65-75% is optimal; stones shallower than 65% may look glassy
- •Inspect corners carefully—even small chips from handling at the wholesale level should be flagged