Scintillation is the pattern of light and dark flashes a stone shows as it, the light or the viewer moves. Our score reads it from the number of facets that reach the surface of the cut.
In more detail
Our scintillation score is not traced. It rises with facet count and levels off, so it is the same in every gemstone. The T73, with 73 facets, scores 80; the T57, with 57 facets, scores 72. A high score means many facets, not more light.
How we measure it
S = 100 × (1 − e^(−f/45)), where f is the number of facets that reach the surface. Buried planes do not count. The Cut Performance Wheel, the cut pages and the Cut Performance Index show it. The Cut Grading Tool uses a different, modeled scintillation that depends on crown and pavilion angle.
Related terms
- Brilliance: Brilliance is the white light that a cut stone returns to the viewer. In our census, it is the share of entering light that leaves through the crown toward the viewer.
- Fire: Fire is the flashes of spectral color that a cut stone sends out. In our census, fire is the share of returned light whose colors leave more than 0.6° apart.
- Facet count: The facet count is the number of facets on a cut. On our cut pages, it is the number of planar faces of the cut's STEP solid.
- Cut Performance Wheel: The Cut Performance Wheel is a free Digital Gemology tool. It draws eight light-performance scores of one cut, in one gemstone, on a wheel.
- Fixed settings: Fixed settings are the constants of our scoring method that we chose rather than measured. They are the same for every cut, so the scores can rank cuts within one gemstone.