Diamond cut is the most important of the four C’s. When purchasing a diamond, it is wise to devote the majority of your budget to the best cut you can afford since cut directly influences a diamond’s appearance. An ‘excellent’ otherwise known as an ‘ideal’ cut is what gives the diamond its fiery brilliance. An Ideal Cut is a cut grading assigned to a diamond that is expertly proportioned to reflect the most light possible, no matter how big or how small the diamond is. A well-cut diamond can also mask less desirable qualities such as a lower color or clarity grading.
Diamond cut refers to the proportions of the diamond. If the facets are lined up correctly and at the proper angles, light will enter the diamond and be dispersed in a magnificent array of color. If a diamond is cut too deep or too shallow it will leak light, have dark spots and not reach its beautiful light-reflecting potential.
| Ideal | Very Good | Good | |
| Depth % | 59%-62.7% | 58.1%-63% | 56.1%-64.3% |
| Table % | 53%-57% | 53%-63% | 53%-65% |
| Girdle | Thin-Slightly Thick | Very Thin Thick | Very Thin – Very Thick |
| Culet | None – Medium | None – Medium | None – Medium |
| Polish | Excellent – Very Good | Excellent – Very Good | Excellent – Very Good |
| Symmetry | Excellent – Very Good | Excellent – Very Good | Excellent – Very Good |