Cut and shape are two different characteristics when it comes to diamonds. The shape of a diamond refers to the outline or form of the diamond as viewed from the top. Popular diamond shapes include round, princess, oval, pear, marquise, and emerald. Diamond shape is a matter of personal preference, and there are no objective standards for evaluating the beauty or value of one shape over another.  The cut of a diamond, on the other hand, refers to how well the diamond has been cut and polished from its rough state. A diamond's cut is the most important factor in determining its beauty, as it affects how well the diamond reflects and refracts light. A well-cut diamond will have optimal light performance, meaning that it will reflect and refract light in a way that maximizes its brilliance, fire, and sparkle.  When evaluating the cut of a diamond, experts consider several factors, including proportions, symmetry, polish, and the overall quality of the cutting workmanship. The GIA has established a diamond cut grading system, which ranges from Excellent to Poor, to help consumers understand the quality of a diamond's cut. In summary, while the shape of a diamond is a matter of personal preference, the cut of a diamond is a critical factor in determining its beauty and value. A well-cut diamond can make even a less popular diamond shape look stunning, while a poorly cut diamond will look dull and lifeless regardless of its shape.