Pearl Luster is defined by the sharpness and brightness of reflections as seen on the surface of a pearl. The Gemological Institute of America classifies pearl luster into five grades.
Pearl Luster
| Grade | Description |
|---|---|
| Excellent | Reflections are uniformly bright and sharp. |
| Very Good | Slightly less defined, fairly sharp, bright reflections. |
| Good | Reflections are not clear but still fairly bright. |
| Fair | Reflections are very fuzzy and weak. |
| Poor | Reflections are non-existent or extremely weak. |