The American Gem Society has been studying diamond cut for several years. Our goal is to develop practical, performance-based cut grading systems for fancy shape diamonds, round brilliants and round fancies.

The AGS Research Team has utilized and combined different approaches to try to explain diamond cut. Some of these are: direct observation, angular spectrum, ray tracing virtual and wire frame models, color-coded photography, OctoNus DiamCalc software.

The new AGS System will take into account the following factors: an observer, a close viewing distance, appearance as distance varies, brilliance, fire, leakage, scintillation, 'spread', tilt, obscuration, girdle thickness, length-to-width ratio, polish, symmetry, durability and taste.

By sharing some information on these factors we hope to:
1. Help the world cut grading community achieve a better understanding of the complex factors that affect diamond performance.
2. Fine-tune our system through constructive feedback and criticism.

Keywords: diamond, cut, research, performance