Diamond Shape

Diamond shape should not be confused with Diamond Cut.  While the two are related, the shape of a diamond refers to the specific form, figure, or outline of the diamond and its particular facets. The shape of a diamond is not analyzed when determining its value; rather the quality in proportion, symmetry and polish of a specific shape are evaluated when grading a diamond. Diamonds with different facet shape, placement and general figure can both be ‘Excellent’ cuts. The grading simply depends on the quality of a cut of a specific shape.

Because some cuts are more difficult to produce than others, and certain cuts involve the loss of a high percentage of rough stone, there are noticeable price variations in price from shape to shape.  The most expensive and most popular diamond shape, for example, is the round brilliant.  This cut requires discarding the highest percentage of rough diamond of all the widely produced shapes on the market. The round brilliant has become the standard shape in the diamond industry. This shape can be found in most pieces of jewelery including diamond earrings, rings, and more. All other shapes are referred to as fancy shapes.

The Round Brilliant, the shape which has become an international diamond standard, was only introduced to the diamond market in the 1920s.  The shape of the round brilliant is based on specific cut proportions discovered in 1919 by Marcel Tolkowsky, a mathematician who came from a long line of Belgian diamond cutters.  In researching diamond proportion for his doctoral thesis at the University of London, he discovered that specific proportions, symmetry and facet placement lead to optimal light performance.  When he published his thesis, “Diamond Design: A Study of the Reflection and Refraction of Light in Diamond”, he outlined specific measurements for every part of the diamond and argued that the round shape allows for cutters to create a diamond with maximal brilliance, scintillation and fire. 

Tolkowsky concluded that the perfect diamond cut should have 58 facets with a culet, a 59% depth percentage, a 53% table percentage, a pavilion depth of 43.1%, crown height of 16%, a pavilion angle of 40.75 degrees, and a crown angle of 34.5 degrees.  Since Tolkowsky published his findings, the Round Brilliant has been adopted internationally.  However, over time, Tolkowsky’s specific parameters have changed just slightly. Today, the table percentage of an Excellent Round Brilliant, for example, may range from 53% to 57%.   Also, many cutters prefer a smaller culet or no culet at all.  Finally, Tolowsky never specified a girdle thickness, which most cutters agree should be medium in thickness to keep the diamond strong.  

Most believe that the Round Brilliant diamond evolved from what was known as the “Old Miner Cut” or “Triple Cut”.  This cut was the most popular diamond cut in 17th century Europe and had facets that were fairly similar to the brilliant diamond cut.  The “Old Miner Cut” evolved into the “Old European Cut” on which Tolowsky based his research.  

Sometimes the Round Brilliant Cut is also known as the American Ideal Cut since it is thought to optimize a diamond’s light performance. It is also one of the most expensive cuts since it takes longer to cut than nearly every other cut and also involves cutting away more rough diamond than most other cuts.  There are a number of other variations on the Round Brilliant including the European Cut, the American Standard Cut and the Modern Brilliant cut. These cuts have proportion standards that are very slightly different and are almost identical in cutting technique. 

Any diamond shape that is not a round brilliant is referred to as a fancy shape. Don’t be confused by their names which include the word “cut”.  Each shape can range in cut grade, depending on its polish, symmetry, and proportion which impact the stone’s overall light performance. The most widely produced fancy shapes are listed below. 

Princess Cut: The princess shape is square or rectangular in shape.  It is usually called a square/rectangular modified brilliant in GIA grading reports. The princess was created in the 1980s and at the time was considered to be quite a radical cut. Princess diamonds are usually cut with either 50 facets (21 crown facets, 4 girdle facets, and 25 pavilion facets) or 58 facets (21 crown facets, 4 girdle facets and 33 pavilion facets) depending on the cutter’s preference. More rough diamond is retained when cutting a princess diamond than when cutting a round diamond.  Because of the high retention of carat weight, princess diamonds are typically more affordable than round diamonds.  Today, the princess diamond it is the most popular shape after the round brilliant and has grown in popularity because of its unique style and clean lines that still retain spectacular brilliance.

Cushion: The cushion shape is square or rectangular with rounded corners and a high crown.  It is based on the Old Mine Cut, the predecessor of the round brilliant.  Because of its high crown, its rounded edges and high number of facets (58 total) it resembles a cushion or a pillow. For this reason it is also known by some as the pillow shape. There are several varieties of cushion shaped diamonds on the market such as the modern cushion, antique cushion, and cushion brilliant. Each has a slightly different facet pattern: some feature steeper crowns, others larger tables or smaller culets. There is no one industry standard for the cushion shape, although there are basic proportional guidelines.  Because the cushion cut was extremely popular from the mid 1800s to early 1900s, it is typically associated with a more antique or vintage feel. It was also cut for candle light, with a soft romantic feel to it.  For this reason it has recently experienced a revival with vintage and antique cuts’ renewed popularity.

Marquise: The marquise shape is a football shape with two pointed ends. Legend says that the Sun King commissioned a diamond cut that resembled the mouth of the famously beautiful Marquise de Pompadour. The cut has an elegance and daintiness about it, and its long ends are thought to make the diamond appear larger than it is.  Its length has also made it popular among women who want their fingers to seem longer, as marquise-set diamond rings are said to give the illusion of elongating the finger of the wearer. The marquise shape is usually cut based on round brilliant parameters with 58 facets including a culet (33 crown facets and 25 pavilion facets). However, variations can yield marquise diamonds with 31 crown facets, and 23 or 21 pavilion facets. Marquise shaped diamonds that are especially long and thin may exhibit a dark shadow across the middle of its face that resembles a man’s bow tie. This is referred to as the bow tie effect and is thought to negatively impact a diamond’s appearance.  More on the bow tie effect.

Radiant: The radiant cut is a rectangular shaped adaptation of the round brilliant cut, typically referred to as “Rectangular Modified Brilliant” or “Squared Modified Brilliant.” The radiant cut was developed in 1977 by Henry Grossbard in New York.  He wanted to bring sparkle and fire to a square or rectangular cut diamond and succeeded in creating the first rectangular diamond cut to employ the round brilliant parameters on both the crown as well as the pavilion.   The most common radiant cut has 62 facets (25 crown facets, 8 girdle facets, 29 pavilion facets), however they can range up to 70 facets total. The radiant cut features cut and truncated corners which can range in length and size.  It is considered to be the first fancy cut branded diamond since it was protected by a patent when it was first introduced to the market, although today it is public domain.  The radiant cut has become an especially popular cut for fancy colored diamonds since its shape, facet alignment and special proportions actually deepen color. Radiant shaped diamonds that are especially long and thin may exhibit a dark shadow across the middle of its face that resembles a man’s bow tie. This is referred to as the bow tie effect and is thought to negatively impact a diamond’s appearance.   More on the bow tie effect.

Emerald: The emerald cut is one of the oldest diamond shapes.  As early as 1447 there is record of Archduke Maximilian of Austria presenting Mary of Burgundy with a magnificent emerald cut diamond ring as a symbol of their marriage engagement, and what was to become the inspiration for the modern day diamond engagement ring.  The emerald cut is a rectangular or square shaped step cut.  Step cuts, like the emerald cut and Asscher cut, have well defined rows of step-shaped facets on the diamond’s face which look like a staircase.  The emerald cut has a total of 58 facets (25 crown facets, 8 girdle facets and 25 pavilion facets).  Emerald cuts are typically less brilliant and firey that brilliant cuts due to their large flat table, their angles and facet shapes which appeal to people who prefer a classic understated look.  Additionally, the diamonds used for emerald cuts are typically very high quality since any blemishes, inclusions or color pockets are easily visible in an emerald cut. 

Asscher: The Asscher cut was invented in 1902 by Dutch diamond cutter, Joseph Asscher, one of the two famous Asscher Brothers of Holland who are known for cutting some of the most celebrated diamonds in history. The shape of the Asscher is square with the corners deeply cut, adding a somewhat octagonal look to the stone as well.  Inspired by Renaissance table cut diamonds, the Asscher features an unusually small table, a high crown, heavily defined step facets, a long pavilion and a square culet.  This made it very different from the popular cushion cut of the day which had soft corners and a rounded, brilliant face.  It was designed to draw the viewer’s eye to the center of the stone while giving it depth and complexity. The Asscher cut peaked in popularity around the 1920’s when it declined in production.  For this reason, it is still associated with an art-deco, antique, vintage feel.  In fact, it was nearly impossible to obtain an Asscher cut diamond outside of the antique market or estate jewelry market till 2001 when a revamped Asscher cut was re-released.  The modern Asscher cut is a bit more octagonal in shape and far easier to come by than original Asscher cut diamonds which are still a rare commodity. 

Oval: The oval cut is an adaptation of the round brilliant, developed by Lazare Kaplan in the early 1960s.  Its official name is “Oval Modified Brilliant” and typically features a total of 56 facets based on the round brilliant pattern, although more facets can be added to enhance the stone’s brilliance. Oval diamonds have seen an upturn in popularity recently, and when mounted in a ring is thought to elongate the finger of the wearer. Oval shaped diamonds that are especially long and thin may exhibit a dark shadow across the middle of its face that resembles a man’s bow tie. This is referred to as the bow tie effect and is thought to negatively impact a diamond’s appearance.   More on the bow tie effect.

Pear: The pear cut is an adaptation of the round brilliant and therefore its official name is “Pear-Shaped Modified Brilliant”.  It is a combination of the round cut, marquise cut and oval cut. Usually it has 58 facets in a pattern that is based on the brilliant pattern; however, the pavilion main facets can range from 4, 6, 7 to 8. Diamonds of this shape are typically referred to as pears when their tip is pointed downwards and teardrops when their tip is pointed upwards. Like the marquise shape, the pear shape diamond mounted in a ring is thought to elongate the finger of the wearer when the tip is pointing upwards.  Many of the most well-known and celebrated diamonds were cut into a pear shape, such as De Beers 203 carat internally and externally flawless Millennium Star diamond and the 69 carat Taylor-Burton diamond. Pear shaped diamonds that are especially long and thin may exhibit a dark shadow across the middle of its face that resembles a man’s bow tie. This is referred to as the bow tie effect and is thought to negatively impact a diamond’s appearance.  More on the bow tie effect.

Heart: The heart cut is an adaptation of the round brilliant and therefore its official name is “Heart-Shaped Modified Brilliant”. It is essentially a pear shaped diamond with a cleft at the top. This romantic cut usually has a total of 59 facets; however the number of pavilion main facets can vary between 6, 7, and 8.  While the cut itself requires outstanding skill, it can be an advantageous way to approach a diamond with a large and unattractive inclusion.  If the cut is planned well, the inclusion can be removed at the clef of the heart, creating a higher quality diamond in the cutting process.  Because the heart shape is so difficult to achieve, most heart shaped diamonds are one carat or above. Heart shaped diamonds that are especially long and thin may exhibit a dark shadow across the middle of its face that resembles a man’s bow tie. This is referred to as the bow tie effect and is thought to negatively impact a diamond’s appearance.  More on the bow tie effect.