What is the key difference between "icing" and "brilliance" in diamond terminology?

In diamond terminology, the distinction between "icing" and "brilliance" is important for understanding how light interacts with a diamond. Icing refers specifically to the surface sparkle or the visual effect that can be seen when light hits the facets of a diamond. This term captures the attractive, lively visual characteristics that can be noticed when observing how a diamond glistens under light.

In contrast, brilliance encompasses the overall light return of the diamond, which is the way light enters the stone, reflects internally, and then exits the diamond. Brilliance is determined by the cut, clarity, and proportions of the diamond, affecting the total amount of light that is reflected back to the viewer's eye. This quality contributes significantly to the overall appearance and presence of the diamond.

Understanding these two terms helps in evaluating a diamond's performance and aesthetic qualities. Icing adds to the visual appeal but is more about surface phenomena, while brilliance is concerned with the overall impact and light performance of the diamond. Thus, the definition provided accurately captures the essence of each term.