Scintillation is the term used for the changing colors, the radiance and sparkle of the rays when the stone is moved or when the light source changes.
The quantity of light reflection generated - irrespective of the material depends on the number, size and symmetrical arrangements of the facets, as well as on the quality of the- polish.
The very smallest brilliants in sizes 0.01 to 0.03 ct often appear lifeless and "diffuse", and look like a milky white dot, because the light reflections produced by the tiny 57 facets can no longer be resolved by the human eye.
On the other hand eight-cut diamonds of similar size with a total of only 16 facets look more brilliant and more transparent, because the smaller number of reflection's can be individually better resolved. On the other hand, many large historical diamonds appear lifeless, because the large-surfaced facets do . not evoke sufficient light reflections. Only when, during re-cutting, they receive additional facets, which increase the number of reflections, do they shine out in a lively color play.
At this point the importance of the quality of the cut may be stressed once more. Only it can bring the beauty of a cut diamond to full culmination. Even a diamond with inclusions, when perfectly cut, appears no less resplendent than a loupe-clean stone and ranks equally with it as a jewel.