Luster is one of the dominate factors in judging a good pearl. Different from the harsh diamonds, pearl is eye-catching with soft shine. The value and beauty of pearls depend, of course, on a number of factors. The degree of finish can be a decisive factor. The so-called finish degree simply means the defect size and distribution.
The common pearl flaws we can see are as follows:
Bump and Welt:
Irregular bumps are formed from excessive secretion of nacre. They do not affect the basic pearl shapes, but we can see them easily with our naked eyes.
Pinpoint and Pimple:
Generally speaking, protruding dots, pinpoints and pimples are small on the pearl surface. They are not easy to be seen unless you observe carefully.
It is caused by the imbalance in the secretion of black skin. The dark spots often concentrate in one point and they can be washed away in the bleaching process.
The uneven secretion of nacre weakens the luster, but it does not affect the pearl durability. However, if the dull spot is formed by human body, cosmetics or hairspray, the nacre will be fade off and durability will be affected as well.
It is common to see clips in the part of drilled hole of the pearl surface, especially for the pearls with thin nacre. It not only affects the appearance, but also gathers dirt.
Small cracks look like wrinkles and large cracks are same as hairs. The cracks in the pearl nacre affect the durability in a severe way.