The Princess cut has become the choice shape second only to the round brilliant. A relatively new cut, it combines the square or rectangular cut with the brilliance of a round brilliant but look for a different set of ratios; around 65-72% depth and 75-78% table for maximum brilliance. Deep cut stones are common and should be avoided for the same reasons as the round. The choice between a square stone and one that is rectangular is a matter of personal taste although perfectly square cuts are rarer and priced accordingly. Watch for chipped corners and feather type flaws near the corners which could cause the diamond to chip during wear. Also watch for overly thick girdles as these are common and will result in a small looking stone. One of the advantages of the princess is its ability to hide flaws. An SI2 princess will probably appear eye clean while the same flaws would be apparent in other cuts.

  The Quadrillion cut patented by Ambar Diamonds is a perfectly cut modification of the princess; it is considered the ideal cut for square shapes. That is not to say that you won't find an ideal cut princess, but the Quadrillion is always cut to ideal proportions with perfect symmetry. The 49 facets of the Quadrillion are based on a different formula than the princess to maximize brilliance without regard to maintaining carat weight. Expect the Quadrillion to carry a 10-20% premium over the princess and these diamonds are available only from Ambar.

The princess (and Quadrillion) are also the primary diamond that is used in invisible settings where the girdles of the diamonds are notched so that multiple diamonds are locked together with one another. If you consider this type of setting make sure you have a solid guarantee for stone replacement by the manufacturer as is impossible for the average jeweler to replace a lost invisible set diamond

  The emerald cut was at one time quite popular but new cuts such as the Princess and Radiant have basically replaced and with good reason. While a perfectly cut emerald shape has some measure of refractive brilliance it is no match for its contemporaries. The preferred ratio is 1.5:1 but again this is a matter of personal taste with little effect on brilliance. There will be some refraction of light but little of the scintillation of the newer "emerald" shapes. Due to a lack of supply the prices are comparable to rounds even though there is less demand.

  The triangle cut diamond is most commonly called a trillion and is more than a simple triangle cut which you will only find used with colored gems and CZ's. The trillion cut uses the same basic facet pattern as that of a round but applied to an equilateral triangle. Due to the points the brilliance will be similar to the ends of a marquise. This cut is most often used in pairs as side stones for a round or fancy cut diamond and as a result any evaluation of brilliance is relative to the center diamond. The trillion works very well with fancy shapes but will need to be very carefully matched with a round brilliant. A round brilliant that is less than ideal or near ideal cut may look "washed out" compared to the trillion. There does not seem to be a set of proportions that maximizes brilliance but trillions that are cut deep will simply cost more due to the increased carat weight. There is a branded trillion called a "trilliant" by Henry Meyer Diamond Inc. which are sold in perfectly matched pairs. While these branded trillions are priced higher per carat they usually offer a better bargain due to their precise cutting and matching and are generally diamonds with less wasted depth which means you will get the same size measurement as a standard trillion for the same money.

  The heart shape is one of the most difficult cuts to execute properly and thus there is a wide range of cutting qualities in this shape. Most heart cuts are blocky and require some imagination to see the “heart”. They also tend to have less than desirable brilliance. I have however seen perfect heart cuts as small as 1/3 of a carat; you just have to be patient and look at dozens of stones. The perfect heart will be just that, very well defined lobes and a nicely shaped profile. As with any diamond, look for one that is not too deep or too shallow. A properly proportioned heart will be very brilliant although still less so than the ideal round.

  The baguette cut (straight and tapered) is a simple modification of the emerald cut. It has sharp corners and only 11 to 15 facets including the table so it will have a glassy effect. These diamonds are used as side stones or in linear sequence to achieve a multifaceted, continuous look. I mention this shape only because it is very common in diamond jewelry although never as a center stone. I am not a big fan of the baguette (the name derives from the French loaf of bread for its long shape) because it does little to enhance the diamond’s brilliance and also because they are so darn expensive! For about the same money you can get small princess cuts or princess cut baguettes which will be much more brilliant.

The Flanders Brilliant is still protected by patent and trademark since its introduction in the 1990's. It is another example of the application of a modified round brilliant cut applied to a square diamond. This design is considered by some to be superior in brilliance to the round brilliant and the most brilliant of square cuts. As with the radiant there will be stones which are well cut with what would be termed "ideal" proportions as well as stones that are not as well cut in the ever present attempt to maximize weight. Because of the unique nature of the cut it is imperative that you compare a number of Flanders brilliant cuts to select one that maximizes brilliance. Since this is a branded cut protected by patent, expect to pay a slight premium over a similar quality round and keep in mind that this cut (and the radiant) is used on the entire spectrum of qualities, including the champagne color range.

The Tycoon Cut is a departure from the other branded rectangle shapes with a radical top design which is reminiscent of the early French cut. It is marketed as the “only diamond with a diamond on top”. As with all of the branded cuts it is billed as the most brilliant of cuts by its designer Toros Kejejian. It is said to reflect 50% more light than traditional cuts. I believe this would be true when compared to the standard emerald cut but would suggest that you compare it to other fancy rectangle cuts yourself. The Tycoon cut diamond is available loose but you may need to find the jeweler who has an exclusive in your area.

The CrisCut is a patented and trademarked design by Christoper Slowinski of Christopher Designs. The cutting pattern was developed with the aid of the computer and the result is a very unique and brilliant redesign of the emerald step cut. The most notable feature are the triangle facets used throughout the 77 facet design which produce unusual scintillation and brilliance. Most of these diamonds are set in finished jewelry by Christopher Designs so loose stone price comparisons are difficult. You will need to find a jeweler that represents the company as the availability is limited.