For many, deciding on a diamond shape will be the first step in choosing a diamond. Different than “cut” which refers to how well or poorly a diamond is faceted, “shape” refers to a diamond’s overall physical shape and style of cut. I’ve listed the most popular below. Click on one to jump to that particular shape in the article, or scroll down to read about them all.
- Round Brilliant
- Princess Cut
The round brilliant is by far the most classic and popular shape for diamonds. Its mathematically precise proportions where developed over a hundred years ago by a Russian mathematician searching for the cut that would maximum a diamond’s fire and brilliance. Its 58-facet cut, divided among its crown (top), girdle (widest part) and pavilion (base), is calibrated through this precise formula. These stones will exhibit the most sparkle of any shape. The round brilliant-cut is so popular that any other shapes are considered “fancy cut.”
Princess-cuts are the most brilliant type of square cut, and are currently very popular, especially in reproduction antique or art deco style settings. However, this type of cut is relatively new, dating back only to 1960. The princess has pointed corners and is traditionally square in shape. If you are looking for a rectangular shaped diamond, and have the budget, go with an emerald-cut instead. A rectangular cut princess is not considered ideal. However, because of this, you can can get a better deal on them. When choosing a color grade, try to go with something I color or better or the color may be slightly visible in its corners. One of the advantages of a princess-cut diamond is that they tend to make inclusions look less visible due to the unique cutting and polishing technique that is used. Therefore great clarity is not as important as with some other cuts. For a princess diamond shape that is square, look for length-to-width ratios as close as possible to 1.0.
The emerald-cut is a form of step cut characterized by a square or rectangular shape and parallel rectangular facets. This cut features beveled corners which creates an octagonal outline to the stone. The emerald-cut was extremely popular during the Art Deco period, but has fallen from fashion because of its relative lack of brilliance. Because both the pavilion and crown are comparatively shallow, step cut stones are generally not as bright and never as fiery as brilliant cut stones. Instead this elegant cut accentuates a diamond’s clarity (even the slightest flaw will be highly visible), whiteness, and lustre (and therefore good polish). It is important to choose a stone with excellent clarity, VS2 or better, and good color, I or better. The most popular and classic length to width ratio for an emerald cut diamond is between 1.3 and 1.4. Due to the current vogue for brilliant and brilliant-like cuts, emerald-cut diamonds offer a good value.
Asscher-cut diamonds look similar to an emerald-cut but are square in shape with the cut off corners being more pronounced. They are less brilliant than a princess-cut, and like an emerald-cut show off the transparency of a stone. The Asscher-cut is older than the princess-cut, and is named after the Asscher Brothers who developed the cut in the early 1900s. It is important to choose an Asscher-cut diamond with high clarity because these diamonds feature a large table. They will also tend to show off any hints of color, so choose an Asscher with I color or better. Asscher-cut diamonds are meant to be square, so it is best to choose a diamond with a length-to-width ratio as close to 1.0 as possible. This classic cut is currently experiencing a resurgence in popularity especially among high-end consumers.
Marquise-shaped diamonds are currently not very popular and thus you can get a good deal on them. Expect to pay about 25% less for a marquise than an equal quality round diamond. There are ideal proportions for marquise shaped diamonds, but often this is disregarded in order to maximize carat weight. For the best cut marquise shape, look for length-to-width ratio as close to 2.0 as possible. Anything closer to 1.0, and the diamond will look too squat. Anything closer to 3, and the diamond will look to long and narrow. These are not considered well-cut. Marquise shaped diamonds usually make me think of jewelry from the 1990’s when they were popular, set long ways, in engagement rings with prong settings. However, I think they can look quite pretty and infinitely more modern if bezel set instead.
An oval-shaped diamond is the closest fancy cut shape to the round brilliant, and they will posses a similar degree of brilliance. They can, however, make fingers look more slender and are a more unique, but still classic choice. Another bonus, is that their elongated shape will make them appear larger in size than a round diamond. For the most traditional and ideal proportion, look for length-to-width ratios between 1.33 and 1.66.
The radiant-cut is a relative newcomer, as it was only introduced a little over 20 years ago. This cut is a unique hybrid of the round brilliant-cut and the emerald-cut, combining the fire of round diamonds with the elegance of emerald-cut diamonds. With an intricate 70-facet cut (even more than round brilliants) radiant diamonds offer tremendous brilliance. They vary in shape from square to rectangular. If you desire a square shaped radiant, look for a length-to-width ratio between 1 and 1.05. If you prefer a rectangular shaped radiant, choose a length-to-width ratio of 1.15 or greater.
This brilliant-cut diamond is is a mix between a round and marquise-cut, as it is rounded on one end and pointed on the other, like a teardrop. They are renowned for their high levels of brilliance, boasting 58 radiant facets. I tend to think pear shaped stones are more appropriate for earrings and pendants, but if you decide to buy one for an engagement ring, look for a length-to-width ratio between 1.45 and 1.75 for the most pleasing proportions.
This shape has been around for almost two centuries and reached it’s peak of popularity around 1900. They have a beautiful antique look, with a soft, diffuse brilliance. Cushion-cut diamonds are square or rectangular in shape with rounded corners and fewer larger facets than most brilliant cuts. These larger facets highlight the diamond’s clarity, just like an emerald or Asscher-cut, so be sure to choose one with good clarity, SI1 or better. The standards for cushion cut vary more than most other shapes. Just look for the one with the most brilliance. Although they are generally less brilliant than round brilliant-cuts, cushion-cut diamonds are often considered to have better fire (the rainbow of color that reflects out of some diamonds). For a cushion-cut diamond that is square, look for length-to-width ratios between 1 and 1.05. For a more rectangular shape, look for length-to-width ratios more than 1.15. As cushion-cuts are currently not very popular, you can as with marquise-cut diamonds, expect to pay at least 25% less than for a the same quality round diamond.
A heart-shaped diamond is an obvious romantic shape for an engagement ring, as it is the ultimate symbol of love. It is considered a modified brilliant-cut and most high-quality heart-shaped diamonds are cut with 58 facets, just like a round-brilliant. When choosing a color grade, look for a grade of I or better or else color may be somewhat visible in its corners. For a more traditional heart-shaped diamond, look for length-to-width ratios between .90 and 1.10.
Accent Stone Cuts
The below diamond shapes are often used in wedding bands or as accent stones in engagement rings but will almost never be used as a center stone. Most likely, if you buy them it will be as pre-set stones in a setting or band, rather than as a loose stone as may be the case with the cuts described above.
Baguettes are a long rectangular shaped cut similar to an emerald cut but with square corners. Tapered baguettes taper in slightly at one end and are often used on either side of a main stone to set it off, and adding more brilliance to the setting. The fatter side is set towards the center stone with the thinner side set to taper into the ring. Regular rectangular shaped baguettes can either be set lengthwise in a thinner band, or they can be set vertically in a wider band, oftentimes using a channel setting to protect their corners from chipping. Using different sized baguettes placed vertically in a stepped pattern can create a dramatic look.
Triangular Brilliants, known as Trillions and Trilliants, are mixed cuts with three sides. Their sides can either be straight or slightly curved. Trillons are often used as side stones for other diamond shapes. I personally, do not think they look good as a center stone in an engagement ring. When cut to proper proportions, trillions are very bright and lively stones and will play up the brilliance of any center stone they flank. The optimal length to width ratio for trillions-cuts is 1:1.