These "flaws" are naturally occurring characteristic and may not always detract from the pearl's beauty or value. Surfaces are usually categorized into one of four grades.
- Clean - exposed face of pearl will be spotless after
the pearl has been set or included in a pearl strand.
"Clean" pearls are used for the finest jewelry, especially in strands and matched pairs.
- Slight - minor flaws on the surface that do not
detract from the beauty of the pearl
- Commercial - many blemishes, sometimes heavy pitting
on the pearl's surface. If the pearl has good luster,
they are used in manufactured jewelry and affordable
strands.
- Low Grade - pits or blemishes dominate the surface of the pearl.