When seeing a title such as "ideal cut" one may wonder as to why all diamonds are not cut to become ideal cut diamonds. There are numerous reasons for this, including the properties of the natural raw diamond, monetary reasons and aesthetics.

For one thing, most raw diamonds cannot be cut for use as jewelry-quality diamonds, much less be cut to ideal cut ratios. Out of the few raw diamonds found that can be utilized for jewelry, only a small percentage of these have the physical properties to be cut to the ideal cut round brilliant proportions. This is not to say that they are the most rare of diamonds, as they are not, but simply to note that due to such variables as naturally occurring inclusions (flaws within the diamond's crystalline structure, such as spots of other minerals, and cleavage lines) it is impractical, if not impossible, to cut all jewelry quality raw diamonds into ideal cut round brilliant diamonds.

Another reason for not using the ideal cut round shape for all diamonds is simply that the ideal cut is not ideal for all people and all occasions. The ideal cut emphasizes particular aspects of the diamond, such as the brilliance and fire. However, these characteristics are primarily brought out in bright, modern lighting. The more romantic lighting of candlelight and gaslight is more complementary to older diamond cuts, such as the rose cut, and the step cuts, such as the emerald cut. While round diamonds, ideal cut or not, enjoy a high level of popularity diamonds themselves are as unique as the people who own them. Even though the round ideal cut is a popular choice, it is by no means the standard.

In short, not all diamonds are ideal cut diamonds because not all can be, not all are monetarily able to be, and not everyone wants them.

There are also monetary reasons for not choosing ideal cut diamonds. When an experienced diamond cutter is examining a raw stone of jewelry quality, the cutter looks for the flaws, but also for the cleavage points. It is at these cleavage points in the raw stone that the cuts must be made, or the entire diamond could shatter. An experienced cutter can assess what diamond shapes can be brought out of a raw diamond, and has to take into consideration points such as which shapes are being asked for by the owner of the diamond, as well as which shapes are the most feasible to cut and sell. While ideal cut rounds are popular, they can often waste an enormous quantity of the raw diamond in the cutting process if the cleavage points do not accommodate the round ideal cut shape. Even when round brilliants can be brought out of the raw diamond, the ideal cut can not only require more time, but it could also reduce the carat weight of the finished diamond, thus reducing its value.