Light performance cut grade system in its performance based diamond cut grade system, all facets of a diamond are measured in three dimensions rather than two dimensions (vs proportion based grading still using by other leading labs).
The measurements are used by a ray tracing computer program to trace light rays traveling through a diamond.
The program shows the quantity and quality of the light being returned to the viewer. in addition to proportion, symmetry, and polish, we also consider brightness, dispersion, leakage, contrast and spread in assigning the final cut grade angular spectrum evaluation tool (aset).
The aset uses the angular spectrum to display and evaluate the optical performance of diamond.
The device simulate the 3 type of lighting conditions which affect the performance of a diamond: direct light (most intense, most desirable), reflected light (less intense, little or not desirable), obscured light (no intensity, block by the observer) and leakage (most unwanted element).
Color from the aset image reflected such condition.