Cut refers not only to the shape of the diamond, but also its measurements and proportions. Below are some images of today's most popular shapes.

Round Diamonds
The most popular modern cut is the round diamond, officially called Round Brilliant. It has 58 facets which reflect maximum light and sparkle. More than 75% of all diamonds sold are round diamonds.
Princess Diamonds
Extremely popular in recent years, the princess cut diamond has refractive properties almost equal to the round brilliant. Perfectly square, or ever-so-slightly rectangular, the princess is the preferred square cut shape over radiant.
Emerald Diamonds
This elegant cut is typically reserved for larger diamonds of higher clarity and color, because the step-like faceting provides less opportunity to mask inclusions or imperfections of lower grades.
Radiant Diamonds Radiant
The radiant cut diamond is essentially an emerald cut, but with more facets, which gives it increased fire and brilliance. It has more facets than a princess cut diamond and the corners are trimmed like the emerald shape. It produces virtually as much brilliance as the round brilliant cut, and was first seen on the market in 1976. Popularity of the radiant cut has jumped dramatically in the last few years.
Asscher Diamonds
The Asscher is, in essence, a square emerald cut with 57 facets. Like the emerald cut, its step-like faceting provides less opportunity to mask inclusions or imperfections. It is quickly becoming a favorite.
Marquise diamonds Marquise
Named after the Marquise de Pompadour, this dramatic, elongated diamond shape is stunning when cut within the desired parameters of approximately 2 to 1 length to width ratio.
Oval Diamonds Oval
The luxurious oval shaped diamond is the most brilliant of all the fancy shaped diamonds because its shape is nearest to the round. Stunning by itself or as a 3-stone anniversary ring with 2 matching oval stones on the side.
Pear Diamonds Pear
Also referred to as the tear-drop shaped diamond. When set in a ring, the point of the diamond is typically worn facing outward to lengthen the appearance of the finger. Also a great choice for pendants!
Heart Diamonds Heart
Heart shaped diamonds are feminine and delicate. This shape is very difficult to cut and often hard to find. Some people prefer a heart shape diamond for sentimental purposes.
Trillion Diamonds
The trillion shape diamond has 50 facets and was developed in the 1950's. Trillions have a very large surface area and often appear much larger than they actually weigh.

The cut of a diamond has a tremendous impact on its final brilliance, fire, and sparkle. Numerous studies have been conducted to determine the ideal cut for a stone. Many variations of cut have been tried, from changing the number of facets to changing the angles of the crown and pavilion, to changing the proportions of the size of table (the top of the stone).

Although opinions of what constitutes and "Ideal" or "Premium" cut proportions vary depending on the source, there are certain ranges that are generally considered to provide the most desirable fire and brilliance from a stone. These ranges cause the light entering the diamond to be reflected back through the table (top), not through the sides or bottom.

Anatomy of a Diamond
Facet: Any flat polished surface of the diamond. Round diamonds traditionally have 57-58 facets.
Diameter: The width of the diamond measured through the widest part, which is the girdle.
Table Facet: The large top facet of a diamond. It is also the largest facet on the gemstone.
Table Percentage: The relationship between the width of the table facet and the width of the girdle (diameter), expressed as a percentage.
Crown: The upper portion of a cut gemstone, from the girdle to the table.
Girdle: The widest part of the diamond, the narrow edge that separates the crown from the pavilion. An extremely thick girdle can add significant weight without a noticeable size increase to the face-up appearance of the stone.
Culet: The tiny facet on the pointed bottom of the pavilion. This is generally considered to be the 58th facet on a round diamond. Since most modern-cut diamonds donÃt have a culet, they only have 57 facets.
Pavilion: The lower portion of the diamond, from the girdle to the culet.
Total Depth: The height of a gemstone, measured from the culet to the table.
Total Depth Percentage: The relationship between the total depth (height) and the girdle (diameter), expressed as a percentage.

A diamond's cut is graded by several measurements. Deviations from acceptable standards allow light to pass through the diamond, which in turn detracts from its overall brilliance and final beauty as is shown in the graphic at the top of the page. Both a shallow cut and a deep cut cause the available light to be reflected out the bottom of the stone instead of being reflected back to our eyes.

Light is lost out the sides causing the diamond to lose brilliance Perfect brilliance and sparkle Light escapes out the bottom causing the diamond to appear dark and dull

In addition to the significant difference in brilliance and light return there is a difference in the face up appearance of cut variation in diamonds. Shallow stones have a larger total diameter, so they appear bigger which may seem like an advantage, but the loss of brilliance is not desirable. Deep stones will have a smaller diameter for their size and will not look as big or face up as comparable stones of the same weight.

Historically, round diamonds have been the most popular and most widely available shape of diamond. Because of this, researchers have spent most of their time and energy on perfecting the angles and percentages that should appear in a round stone.

Ideal Very Good Good Fair & Poor
Table % 53% - 58% 53% - 61% 53% - 65% 53%< or > 65%
Depth % 59% - 62% 58% - 63% 57% - 64% 56%< or > 64.5%
Girdle Thin - Slightly thick Very thin - Slightly thick Very thin - Very thick Extremely Thin; Extremely Thick
Culet None - medium None - medium None - medium Slightly Large; Extremely
Polish Excellent - Very Good Excellent - Very Good Excellent - Good Fair and Poor
Symmetry Excellent - Very Good Excellent - Very Good Excellent - Good Fair and Poor

Although other diamond shapes follow many of the same principles, the ranges are wider and the percentages are different. These shapes (any shape other than round) need to be evaluated on overall beauty and on whether the shape is pleasing to the eye. See the descriptions under shape for more information. As illustrated in the chart above, there is a range of proportions that will provide excellent brilliance and fire. Diamonds that fall within the top three categories above will result in a beautiful diamond that will sparkle in any light.

Polish represents the detail work in the cutting process. The polish grade describes how well the cutter was able to bring out the luster or shine in the facets. It also relates to the smoothness of the diamond's facets. With poor polish, the surface of a facet can be dull, and may create blurred or lackluster sparkle.

The symmetry grade refers to alignment of the facets. If you imagine the crown facets as windows and the pavilion facets as mirrors, symmetry relates to how well they are lined up. If the angles and the alignment are not exact, the amount of light being returned by the pavilion facets (mirrors) will be drastically reduced.

For the past few years, the Gemological Institute of America (GIA) has been working on an industry wide review of the accepted standards of cut. While the final results have not been published, basic information has been released. The conclusions seem to point to several distinct combinations of table and depth proportions that result in equally brilliant diamonds. These combinations are a departure from having only one standard range of ideal cut that was acceptable in the past. Anyone who has graded a significant number of diamonds has come across many beautiful diamonds with incredible brilliance that do not conform to those earlier standards of cut.

Our Take:
We hope you just read the paragraph immediately above this, because it points the new direction our industry is going, which is a departure from the rigid parameters of the traditional ideal cut and embracing the acceptable variances of premium and good cuts. In keeping with that, we prefer diamonds with slightly larger tables because the table is the window we look through to see into the diamond. In general, we favor a table percentage between 57% and 64% which includes the Very Good, and Good categories.