The round brilliant cut diamond is by far the most popular shape, and accounts for about 3 out of 4 diamonds purchased today. The modern ideal proportions for the round brilliant cut diamond (sometimes called the American Ideal Cut) arose from a mathematical thesis written by Marcel Tolkowsky and published in 1919 entitled, "Diamond Design: A Study of the Reflection and Refraction of Light in Diamond". Its 58-faceted design (33 crown and 25 pavilion facets) produces the greatest brilliance, dispersion and scintillation among all the major shapes.

However, there are several other shapes, called fancy shapes or fancy cuts, which with the exception of the emerald cut, are also brilliant cut or modifications thereof. They are frequently chosen as the center stones in rings and other jewelry (shown below in their face-up views).

There are basically three types of cutting patterns, the brilliant cut, the step cut and the mixed cut (a combination of brilliant and step cuts). Sometimes diamonds with modified cuts are described both as to shape and faceting pattern in order to minimize confusion. For example, an oval shaped stone, which has a brilliant cut crown and a step cut pavilion, might be referred to as a "modified oval" or an "oval mixed cut".

Some of the fancy shapes are better suited for retaining the maximum weight of the more flat forms of diamond rough called macles and flats, and many are also cut from the less perfectly shaped octahedral and dodecahedral crystals. There are many other shapes (trilliant, bagette, etc.) and many branded cutting patterns which occupy specialized niches and more limited market positions, but we will not cover them here.

Factors important in selecting a fancy shaped diamond include all of the 4C's as they apply to the round shape. However, additional considerations come into play when considering fancy shapes such as the overall appearance of the outline of the girdle of the stone, the "bow tie" effect and the length-to-width ratio. Finally, one may ask, how does shape affect price? So here we will consider each shape separately and the factors which are important in how they impact beauty and price.

Currently there is no widely accepted "ideal" range of proportions for the fancy shaped diamonds. However, these may be developed in the future because it is known that the American Gem Society is working on this issue (see www.gemappraisers.com for details. This is probably the best classification of cut proportions in fancy shapes currently available.)

When looking at the general appearance of fancy cut diamonds, make sure that the stone is appealing to your eye and that it is bilaterally symmetrical. In other words, if you draw an imaginary line down its center length or across its width (excluding heart and pear in the latter case), one half of the stones should be shaped exactly as the other half. Also look at the shape of the pavilion, especially on emerald cuts, from all angles to make sure it isn't too deep and doesn't bulge excessively, an indication of extra weight retention and perhaps a reduction in light return (brilliance).

In many fancy shaped diamonds (marquise, pear, oval, emerald and heart shapes) the pavilion facets do not culminate at a point at the tip of the pavilion, but rather form an edge, called the "keel line". However, for grading purposes this is still referred to as the culet and should be judged accordingly.

Girdle width will vary between greater extremes on some fancy shapes compared to the round brilliant. These include the marquise, pear and heart, where the girdle tends to be thick or extremely thick at the tips of the stone and in the cleft of the heart-shaped cut. Also, the princess cut, which has square corners, may have an extremely thin girdle in these areas. These situations are frequently encountered with fancy shapes, and attention needs to be paid to the potential problems of excessive weight vs. danger of cracking or chipping in diamonds with extremely thick or extremely thin girdles, respectively.

The bow tie effect, observed with the naked eye, is frequently found in marquise, oval, pear and some heart- shaped diamonds, and is considered to be a negative factor if prominent. It arises from the variations in the pavilion facet angles required in cutting stones which are longer than they are wide. The bow tie looks like two dark triangular shapes joined at the point in the center of the stone (below), and is thought to be the result of light leaking from the pavilion. Caused sometimes by an overly deep pavilion, in a well-cut diamond its appearance should be minimal or absent and certainly not a distraction.

Table measurements used in calculating table size are made at the point of their greatest width, and for the pear and heart shape this is not in the center of the stone, but is at the greatest overall width of the stone. This is the same line along which the width of the diamond should be measured in calculating the length-to-width ratio. For the heart shape, the length of the stone is measured in a vertical line, centered over the cleft, as the distance from the top of the shoulders to the tip.

SHAPES

ROUND - Information for the round brilliant has been described on this site in detail under the topics of the 4C's. The round brilliant diamond, being by far the most popular diamond shape is, because of market forces, the most expensive. Rounds make up the vast majority of diamonds found in engagement rings, and are also popular as stud earrings and pendants. You just can't go wrong with a round!

MARQUISE - The marquise (pronounced "mar-KEYS", not "mar-KEY") is usually cut as an adaptation of the 58-facet standard brilliant, with the crown having 33 facets and the pavilion 25 facets of the same type as the round brilliant. However, the pavilion can be cut with either 4, 6 or 8 pavilion mains facets, depending upon the stone's girdle outline. These modifications are also seen in the pavilion cuts for the pear, oval and heart shaped diamonds.

The crown cut is also sometimes modified in the marquise to form what is called a "French tip", where the bezel facet at the point of the stone is eliminated. As an example for comparison, below is a diagram showing what an imaginary hybrid-cut marquise would look like where the upper half of the stone is cut as a French tip and the lower half is cut as a standard brilliant. Note how the elimination of the bezel facet at the point of the stone requires that the adjoining bezel facets become "stretched" to accommodate the space left. French tips are also sometimes cut in pear and heart shaped diamonds.

The length-to-width ratio is important to a stone's appearance, and for the marquise shape the preferred range is 1.75-2.25: 1.00. Marquise diamonds frequently show a bow tie, so try to find a stone in which this is minimal or absent. This shape of diamond in a ring accentuates the length of the fingers.

As a % of the diamond's width, the better cut marquise will have table % in the range of 53-63% and total depth % (crown+girdle+pavilion) of about 58-65%.

The cost of a 1ct., D, IF marquise is about 20% less than that of an identical round diamond. For a 1ct., G, VS2 stone, the marquise cut is only about 7% cheaper than the same round diamond.

PEAR - The pear shape, like the marquise, usually has the 58 facet brilliant pattern, but can also be cut with different numbers of pavilion mains of 8,7,6 or 4 facets.

In a pear, look for a well-shaped head and even shoulders with an optimal length-to-width range of 1.50-1.75:1.00. This shape in a ring will make the fingers appear longer. Pear-shaped diamonds work equally well as pendants and are exceptional as drop earrings.

Ranges for the well cut pears for table % and total depth % are about 53-63% and 58-65%, respectively.

The relative cost of a 1ct., D, IF pear shaped diamond is roughly 25% less than an identical round stone, but a 1ct., G, VS2 pear is only 20% less than the cost of an identical round.

OVAL - The oval, as with the above examples, is seen most frequently cut in the standard 58 facet brilliant pattern, but again can have a varying number of pavilion mains facets ranging from 4, 6 or 8.

For ovals, look for even, well-rounded ends with a full body having an optimal length-to-width range of 1.33-1.66: 1.00. This shape of stone in a ring accents finger length, and also works nicely as stud earrings.

Higher cut quality ovals, as with the marquise and pear, have table %'s of about 53- 63% and total depth %'s of 58-65%.

The relative cost of an oval diamond of 1ct., D color and IF clarity is roughly 25% less than an identical round stone, but a 1ct., G, VS2 oval is only 20% less than the cost of an identical round.

RADIANT - The radiant cut is a patented name and cut called a cut-cornered, square/rectangular (depending on the overall shape) modified brilliant on GIA grading reports. It has a total of 70 facets, there being 25 crown, 8 girdle and 37 pavilion facets. The truncated corners may aid in avoiding or minimizing possible chipping problems posed by extremely thin girdle widths in these areas of the stone.

Generally, a ring with a square cut radiant tends to shorten the appearance of the longer fingered hand.

Radiants of higher cut quality will have table %'s of about 59-69% and total depth %'s ranging from about 59-69%. Deep pavilions are often seen on many radiants and princess cuts and contribute to the increased total depth % seen in these stones. However, this extra depth is often necessary to bring out the maximum brilliance in the stone.

The comparative cost of a 1ct., D, IF radiant diamond is roughly 33% less than an identical round stone, but a 1ct., G, VS2 radiant is only about 20% less than the cost of an identical round.

PRINCESS - The princess cut is called a square/rectangular modified brilliant in GIA grading reports. It 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.

This cut of diamond is frequently a square shape and therefore shortens the appearance of the longer fingered hand. The princess cut has sharp, squared-off corners, and if the girdle is extremely thin in these areas, chipping or cracking may occur more easily.

Princess shapes of high cut quality usually have a table % in the range of roughly 60-75% and a total depth % of about 65-80%.

As with the radiant, the cost of a 1ct., D, IF princess diamond is roughly 33% less than that of an identical round stone, but a 1ct., G, VS2 princess is only about 20% less than the cost of an identical round.

EMERALD - The emerald cut is not a brilliant cut, but is called a step cut. Step cuts are comprised of larger, planar facets which act like mirrors. The emerald cut has 58 facets, with 25 crown, 8 girdle and 25 pavilion. Because of the angle, size and shape of the facets, the emerald cut shows less brilliance and fire (dispersion) than the other brilliant and modified brilliant cut diamonds. However, the emerald cut stone reveals a classic and aristocratic elegance and beauty not seen in other cuts.

Because of the open and large, plate-like nature of the facets, it is highly recommended that you consider staying at higher color (D-G) and clarity (IF-VS2) grades than you might with a brilliant cut stone because they are more likely to become visible at lower grades. Also, check to make sure that all the facet edges appear parallel in the face-up position. If they aren't, it can be pretty obvious at times.

The emerald cut offers a touch of regal elegance as the center stone in a ring, and the most attractive proportions are a length-to-width ratio range of 1.50-1.75:1.00. However, some prefer a more square look with a ratio in the range of 1.30:1.00. Obviously, the more square the shape, the more it compliments the longer-fingered hand, and the more rectangular, the better suited it is to the shorter-fingered hand.

The better emerald cut diamonds, like radiants, will have table %'s of about 59-69% and total depth %'s ranging from about 59-69%.

Like both the radiant and princess, the cost of a 1ct., D, IF emerald cut diamond is roughly 33% less than that of an identical round stone, but a 1ct., G, VS2 emerald is only about 20% less than the cost of an identical round.

HEART - The heart shape is a brilliant cut, which can also be modified so that the number of pavilion mains may be 6, 7 or 8.

In a heart cut it is important to look for a perfectly symmetrical appearance where the lobes (top arches) are of even height and breadth, and the overall shape pleasing.

The better cut heart shapes will have a length-to-width ratio of just about 1.00:1.00, with a little variation from about 0.98:1.00 to 1.02:1.00.

This shape is seen frequently in pendants, but is suitable for most any purpose.

The well-cut heart shaped diamonds will have a table % in the 53-63% range, and a total depth of about 58-65%.

Roughly comparable with the pear and oval shapes, the relative cost of a 1ct., D, IF, heart shaped diamond is approximately 25% less than an identical round stone, but a 1ct., G, VS heart is only about 20% less than the cost of an identical round diamond.

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