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Shape
If you are shopping for a diamond, one of the first decisions you will have to make is to choose a shape. Diamonds come in many different and exciting shapes. Selection of a shape should be based on personal taste - choose a shape that you will enjoy looking at every day and that reflects your individuality. For example, one woman might favor the more classic shape of a Round stone while another might prefer the more trendy Asscher-cut. A hopeless romantic might love a Heart-shaped diamond, while a man might be drawn to a Shield-cut or Triangle shaped diamond. In addition to personal taste, one should look for a diamond shape that will flatter the shape and length of the owner’s hand. If a woman has a small hand, for example, a Round or Princess shape is typically recommended. A woman with long slender fingers can also wear an Emerald-cut or rectangular Radiant diamond. Finally, it is good to note that certain shapes (such as Round) cost more than other shapes (such as Pear). The effect of shape on price depends on the size of the stone, supply and demand.

Below we describe the unique characteristics of each diamond shape.

Please note that the shape of a diamond shouldn’t ever be confused with its Cut – though it often is. Shape refers to the basic form of a stone – Round, Oval, etc. Cut, on the other hand, grades the proportions of a diamond given a particular shape. Regardless of shape, a diamond that is cut well will reflect light better and therefore create more sparkle.

Round
The most popular and traditional diamond shape is Round. Round diamonds account for over 75% of diamonds sold today. A Round shaped diamond has a total of 58 facets, 33 on the top and 25 on the bottom. Its name refers to the actual shape of the diamond’s table and crown. The Round shape was based on extensive analysis in light optimization which determined that this shape helps to maximize a diamond’s light display as it allows light to both enter and exit the  crown. In addition, Round diamonds are very versatile, as they can look brilliantly beautiful in many types of settings.

The facet arrangements and proportions of the Round diamond cut in the brilliant style have been perfected over time by both mathematical and empirical analysis. In 1919, a Russian Mathematician named Marcel Tolkowsky, who was a member of a large and powerful diamond family, calculated the cut specifications necessary to create the ideal diamond shape (which later became known as the brilliant cut). Based on his analysis, and along with the development of modern diamond tools and techniques, the Round brilliant diamond was born.

Princess
A Princess-cut diamond has pointed corners and is usually square. However, there are some Princess cut diamonds that are more rectangular in shape. This diamond shape may have either 50 facets (21 crown, 4 girdle, 25 pavilion) or 58 facets (21 crown, 4 girdle, 33 pavilion), depending on how the pavilion is cut. A buyer of a Princess-cut diamond needs to look at the length-to-width ratio to determine which stone will be the most attractive. If the shape of the diamond is closer to a square, the ideal length-to-width ratio is between 1.00 and 1.05. If the stone is more rectangular, then the ideal ratio is greater than 1.10. The ideal setting for a Princess-cut diamond ring is a three stone setting, with two smaller diamonds flanking the center stone. It is important to note that Princess-cut diamonds are commonly referred to as a "square modified brilliant" or "rectangular modified brilliant" on most lab reports.

The Princess-cut was developed in Los Angeles around 1980 by Betzalel Ambar and Israel Itzkowitz. At the time, this shape was considered avant garde but is now one of the most popular diamond shapes.

Cushion
Cushion-cut diamonds, one of the oldest shapes in the history of diamonds, come from the square shape family, but have rounded corners and larger facets to increase their brilliance. Some Cushion diamonds are more rectangular depending on their specific length-to-width ratio. The ideal ratio for a Cushion diamond that is more square is between 1.00 and 1.08. If the stone is more rectangular, however, the length-to-width ratio should be greater than 1.10. Cushion-cut diamonds have an old world charm and a romantic feel. When cut finely, they can display magnificent brilliance. Cushion-cut diamonds look remarkable in most settings, including solitaire, surrounded by pave diamonds, or flanked by two smaller diamonds.

This diamond shape was created around 1830 when diamond cutting and polishing was all performed by hand. It was the most admired shape until the time of modern electric lighting, when it lost some popularity to other shapes. The Cushion-cut is based on the Old Mine Cut, which was a square cut with rounded corners, deeply cut with a high crown, small table and large facets. Today’s Cushion-cut diamond has benefited from the use of modern cutting and polishing techniques. It has 64 facets and resembles a cross between the Old Mine Cut and the Oval shape. Recently the Cushion-cut has experienced a huge comeback and has become an extremely  fashionable choice for engagement rings and other high quality jewelry.

Emerald
The Emerald-cut diamond, similar to the shape of a precious emerald gemstone, is also known as a “step cut” diamond since its facets are cut like a set of steps. An Emerald-cut diamond is more rectangular in shape and has tapered corners. High-quality Emerald-cut diamonds produce dramatic flashes of light due to its long lines. This shape conveys a timeless and sophisticated elegance. The clarity of an emerald-cut diamond is very important since inclusions within the diamond will be more visible to the naked eye. The ideal length-to-width ratio for an Emerald-cut diamond is between 1.25 to 1.45. This ratio applies only to classic Emerald-cut diamonds. Diamonds with a step-cut but with a more square outline fall in a different category of diamonds known as Asscher-cut. In a ring, the Emerald-cut diamond can look stunning set as a solitaire or with smaller accent stones, especially step-cut Trapezoid diamonds.

The Emerald-cut for diamonds was based on the technique originally created for cutting emerald gemstones. While the emerald gemstone is a relatively hard stone, it is vulnerable to breakage, making it difficult to cut. The rectangular step cut with cropped corners was developed to address these issues. Diamond cutters soon discovered that this cut can also be applied to diamonds, and therefore created the Emerald-cut diamond.

Asscher
The trendy Asscher-cut diamond has step-cut facets just like the Emerald-cut diamond, but with a square outline. Its structure - deep pavilion, faceted culet, high crown and small table – brings out the diamond’s inner fire. An Asscher-cut diamond also has unique blocked corners and a pavilion faceted in a “scissor cut” style. The clarity of an Asscher-cut diamond is very important since its flat and broad facets will make scratches, inclusions, or other flaws more visible to the naked eye. When searching for an Asscher-cut diamond, a clarity of VS2 or greater is preferred. There may be some exceptions for diamonds with SI1 and SI2 clarities if their imperfections are not visible to the naked eye. The ideal length-to-width ratio for an Asscher-cut diamond is between 1 to 1.05.

The Asscher-cut was invented by Joseph Asscher, a well-renowned diamond cutter who founded the Royal Asscher Company in Amsterdam in 1854. He is also known for cutting the world’s largest known diamond, named the Cullinan Diamond (3,205 carat). Joseph Asscher created his namesake cut in 1902. It quickly gained popularity since it captured the essence of the Art-Deco movement, which was just beginning to develop at that time. Today, the Asscher-cut diamond is enjoying a strong revival due to its fashionable look.

Radiant
Like its name suggests, the Radiant-cut diamond is one of the most brilliant and beautiful shapes. This cut is the diamond of choice for royalty and is considered by many to be the most regal and elegant of all diamond shapes. Radiant-cut, which typically has 70 facets, is a hybrid between a round cut and an Emerald-cut diamond, depending on whether it is square or rectangular in shape. Radiant-cut diamonds are currently a very popular choice for engagement rings. When purchasing a radiant-cut diamond, the length-to-width ratio should be between 1 and 1.08 if it is a square shape and greater than 1.10 if its more rectangular. Radiant-cut diamonds look beautiful on their own or when set in a pave diamond ring or with two flank stones. It is important to note that Radiant-cut diamonds are commonly referred to as a "cut-cornered square modified brilliant" or "cut-cornered rectangular modified brilliant" on most lab reports.
The Radiant-cut diamond was created by Henry Grossbard in 1977. His groundbreaking technique was based on the Round and Emerald-cut diamonds, combining the best of both worlds. By doing so, Grossbard’s Radiant-cut was able to bring out the full brilliance of a diamond with a square or rectangular shape.

Marquise
The Marquise-cut has an elongated brilliant shape with tapered points on each end. Since it is approximately twice as long as it is wide, it makes the fingers look long and slender. It is important to pay attention to the length-to-width ratio of a Marquise-cut diamond. A well-cut Marquise will exhibit excellent brilliance. However, if the diamond isn’t cut properly, it will result in an undesirable “bow-tie” effect, which means the stone will have a dark black area in the center of the stone in the shape of a bow-tie, greatly reducing its brilliance. The ideal length-to-width ratio for a Marquise-cut diamond is considered to be between to 1.8 to 2.2. This cut looks beautiful set with round or pear-shaped side stones.

The Marquise shape was named after a historical legend involving the French king Louis the XIV. The legend claims that he desired a diamond whose shape would look like and be as brilliant as the smile of the Marquise of Pompadour, his influential mistress and notable patron of literature and the arts. The king’s cutters custom crafted the Marquise-cut shape based on this directive.

Oval
An Oval shape diamond is an elongated Round brilliant cut diamond. Like a Round diamond, it normally has 56 to 58 facets. Its structure flatters the shape of the hand since its length makes the fingers look long and slender. An oval shape is also considered to be very classic and elegant. In addition, when cut finely, an Oval diamond’s brilliance will be as superb as that of a Round diamond. The ideal length-to-width ratio for the Oval is considered to be in between 1.3 and 1.65. The beauty of a ring with an Oval diamond can be greatly accentuated by its setting. An Oval diamond looks best when set in a pave diamond ring or with two smaller flanking diamonds.

The Oval shaped diamond was crafted in the 1960s by Lazare Kaplan. He was a Russian-born diamond cutter who came from a family of jewelers. He was inducted into the Jewelers International Hall of Fame for the development of this breathtaking shape.

Pear
A Pear shape diamond combines the Marquise’s unique taper on the bottom and the Oval’s beautiful rounded edge on top. Also known as the Teardrop diamond, this shape usually has 58 facets and is cut in the brilliant style. The Pear is commonly used to create exquisite rings as well as pendants and earrings. In a ring, the elongated shape of the Pear diamond makes the fingers look longer and slender. In a well-cut Pear diamond, the culet is centered directly below the diamond's table to create the greatest light effect. The ideal length-to-width ratio for a Pear diamond is between 1.45 and 1.75. In a ring, the Pear diamond looks beautiful when set as a  solitaire stone or with two round or baguette side stones.

Heart
The romantic Heart shape diamond is the ultimate symbol of love. Not surprisingly, jewelry with Heart diamonds has become a very popular gift to mark special occasions in a relationship such as Valentine's Day or anniversaries. Only a highly skilled cutter can cut a Heart shape diamond properly since it requires great precision and expertise. An otherwise gorgeous Heart diamond can turn into a lifeless stone if the cutter makes even one small mistake. The Heart’s lobes need to be symmetrical, well-defined, and smooth. The ideal length-to-width ratio of a Heart diamond should be between .90 and 1.10. This means that the diameter of the diamond across its widest perimeter should be approximately equal to its length (measured by running a vertical line from the cleft to the tip of the diamond). The Heart diamond is popular for many kinds of settings in pendants, earrings, and rings.

The origin of the Heart shape diamond remains a mystery. While most people would guess this dramatic shape was developed recently, the Heart shape is conjectured to be quite old. A book written by Jean Baptiste Tavernier in 1665 mentions a 36-carat Heart-shaped diamond. It is speculated that this was the first time the western world came across this cut and that it originated in India.

Triangle
The Triangle shaped diamond, also knows as Trillian-cut, is a stone with a triangular shape cut in the brilliant style. This diamond shape usually has 44 facets - but may contain as many as 50 - and has either sharp or slightly rounded corners. The Trillian’s length, width and depth as specified on a certificate, are not calculated by measuring from tip to tip. The length is the measurement of the diamond’s longest side, while the width and height measure the distance from the longest side to the opposite point. It is important to carefully examine the table of a Trillian diamond since poor cutting or polishing could lead to "windowing," or areas where there is less brilliancy than other areas of the table. Since the ideal Trillian cut diamond is an equilateral triangle, the preferred length to width ratio is approximately 1. The Trillian diamond can serve as a unique centerpiece or accent side stone in a ring. It is also commonly used in necklaces and earrings and is very popular in high-quality jewelry for men.

Leon Finker invented this special cut in Amsterdam in 1978. His technique was actually developed by turning the square shaped Radiant diamond into a triangle.

Shield
As the name implies, the shape of the Shield-cut diamond resembles that of a shield used by warriors in battles. The original Shield-cut has been in existence for many years and doesn’t display full brilliance given its limited number of facets. In 2004, Yerudiam’s diamond cutters, Yossi and Benny Yerushalmi, refined and modernized the Shield-cut to give it more delicate lines and bring out the diamond’s maximum fire. The Shield-cut diamond is often used to create unique dangle earrings, pendants, and cufflinks.

Rose Cut
Rose-cut diamonds are believed to have appeared as early as the 1500s. This cut was developed after the introduction of the polishing wheel led to a major advance in faceting in the middle of the 14th century. As its name suggests, the shape of a rose cut diamond resembles the petals of a rose bud. It has a flat bottom, a domed crown, and its facets meet in a point in the center. The number of facets found in Rose-cut diamonds vary from as small as 3 to as many as 24. The Rose-cut made good use out of diamond fragments and thinner forms of diamond rough (called macles and flats). This style was popular until the early 1900s and was mainly produced in Amsterdam and Antwerp.

Old Mine
During the early 18th century, the Old Mine cut was developed in Brazil, the new center of world diamond production. It is considered one of the earliest forms of the brilliant cut since it has 33 crown facets and 25 pavilion facets - the same 58 facets of the modern Round brilliant. The Old Mine diamond is basically square in shape, has gently rounded corners, and has a cushioned shaped girdle. It is known for its high crown, small table, deep pavilion, and large culet. The Old Mine cut can still be found in some older estate pieces.

Old European
The Old European Cut was born sometime in the 1880s and is therefore commonly found in antique jewelry. It is considered by many to be the predecessor of the modern brilliant round cut. It has a circular girdle, a very small table, a heavy crown, and great overall depth with an open culet on the bottom and a deep pavilion. Most diamonds exhibiting the Old European shape were produced in Europe – thus its name. While an Old European diamond may not display as much brilliance as a more modern diamond, it is greatly appealing to many people due to its old world beauty and unique place in history. Another advantage of Old European diamonds is that they tend to keep more of their carat weight in comparison to modern day diamonds since during their era, diamonds were cut in a rougher and less precise manner.

Half Moon
Half moon diamonds are, not surprisingly, in the shape of a half moon. They are mostly used for side stones. Some half moons are closer to half a Round in shape while others are half an Oval. In a ring, Half Moon diamonds serve as great accent stones for Oval center stones. Half Moon diamonds were first created from broken Round and Oval diamonds. The diamond cutter would look for broken diamonds with the same color and then carefully cut them with the same proportions. Today, Half Moon diamonds are produced in a variety of sizes, shapes, and colors. Then, diamond dealers search for matched pairs so that they can be sold as side stones. It is important to note that like other elongated diamond shapes, a Half Moon diamond will show an undesirable “Bow Tie” effect if its not cut properly. However, when cut well, Half Moon diamonds are full of brilliance, adding a wonderful sparkle to a ring or other piece of jewelry.

Trapezoid
The Trapezoid (or Trapeze-cut) diamond, has four sides – two of which are parallel and two of which are slanted. These diamonds are very popular side stones. They are cut in either the step-cut or brilliant-cut style. Brilliant Trapezoid diamonds are great complements to a Princess or Radiant center stone while step cut Trapezoid diamonds look wonderful with an Emerald or Asscher-cut center stone. Versus other side stones such as the Trillion or Baguette, the Trapezoid is preferred for its larger surface area which creates more sparkle. In addition, many people find it more comfortable to wear since the ends of the Trapezoid don’t extend down between the fingers as the pointy ends of a Trillian diamond often times do. Trapezoid diamonds can be found in a large variety of shapes, sizes, and colors – making it relatively easy to find the perfect matched pair for any ring. The relative size of the Trapezoid to the center stone is a matter of personal taste. However, as a general rule, if the center stone is cut-cornered in shape (e.g. Radiant, Emerald, Asscher), the long edge of the Trapezoid should be equal to or less than the distance between the cut-corners.