The cut of a diamond affects its beauty, value and strength. If you're considering buying a diamond, follow these tips to make sure you understand how to judge a diamond cut first.
Not all cuts are made equal. Diamonds are most beautiful when they are properly cut. And there is definitely an art to doing this the right way. There are always new cutting and polishing techniques that are arising that bring out even more of a diamond's natural beauty. All of the diamonds shapes listed below have guidelines to help with cutting the proper proportions into a diamond. Even the slightly deviance from these guidelines lowers the quality and beauty of a diamond. (Ask your jeweler for more specific details on the cut of your own diamond.)
In general, diamond cuts range in quality from excellent, very good, good, and fair to poor. The better the cut of the diamond, the higher the price will be.
Ideal cut. Almost 100 years ago, Marcel Towlkowsky came up with a cut for round diamonds which sets out the ideal proportions for a diamond. This process is still used today, and is known as an ‘Ideal Diamond Cut'. An ideal cut diamond, when properly cut, should reflect all light. It is a very popular cut of the highest quality.
This link describes an ideal cut diamond: http://www.original-diamonds.com/education_proportions_ideal.php
Round cut. This is definitely one of the signature diamond cuts. Staring directly down at the top of the diamond, it is a circular shape. The crown height is average, but there are definite proportions to this and to the base of the diamond that make this round cut beautiful. (Change up the proportions or angels of the round cut, and the beauty of the diamond will be lost. It will go down in grade from excellent to very good, good, fair or even poor). If cut properly, the crown of this diamond cut gives off the brilliance of the diamond.
This link provides the exact proportions to look for when judging this diamond cut: http://www.armstrongjewelers.com/Diamonds/diaproportion.html
Princess cut. This style of diamond shape is popular for engagement rings. It has a flatter, wider top with a shorter crown height. The top is often cut to look like a square or a rectangle, with both sides of the diamond being symmetrical. This shape is thought to be more brilliant than even the Emerald or the Asscher cut diamond.
This link defines a bit more about a princess cut diamond: http://www.thediamondbuyingguide.com/princess_cut_diamond.html
Emerald cut. As the name suggests, this diamond cut resembles an emerald. Much like a rectangle with the corners angled, this cut boasts a wide, flat top and straight edges all the way around. A signature emerald cut diamond has a flattened tip, whereas the traditional emerald cut comes to a perfect point. The many pavilion facts of the emerald cut allow it to capture and reflect more light.
Here is some other information you may find useful when judging this diamond cut: http://www.bluenile.ca/signature-ideal-emerald-diamonds
Asscher cut. An Asscher cut diamond is similar to an emerald cut in that it is a square with the corners angled. (Thus, it is often referred to as a square emerald cut diamond). However, it has a higher crown since there are more layers or angled edges in it. And it has a deeper-than-normal depth.
This page defines the best proportions for this diamond cut: http://www.original-diamonds.com/education_shapes_asscher.php
When you're looking at diamonds, cut shouldn't be the only thing that you consider. There are actually 4 main C's to look for - clarity, color, cut and carat weight. A fifth ‘C' should be cost. There are diamonds that come with all of these characteristics and it is up to you to judge which combination of characteristics will make up the best diamond for you.