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.
|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.|