In terms of the traditional 4C grading of diamonds, GIL maintains the same strict and
internationally recognized US standards as GIA. In addition to the traditional 4C,
GIL creatively introduced the optical evaluation of diamonds in the process of
continuous improvement of the grading system.
The diamond cutting standards were evaluated more comprehensively and systematically from three aspects,
namely light return, optical symmetry and scintillation.
Gem International Laboratories