As for the choice of pearls, first of all should be clear, fresh water and sea water  beads are two different grades of pearls, as Xiuyu and emerald(jade) should not be equated. choose The same type of beads, its color, luster, mother of pearl layer thickness of mother of pearl , shape defects (spots) and other factors should be comprehensive
considerated when make the  final choice .

Color
There are several ingredients of the pearl pigment. Own pigment (such as white, milk color, pink, black, etc.).
General water beads are the color white (with yellow flavor), if the bead itself is of good quality, manufacturers should endeavor to preserve its character,
but the color preferences of all ethnic groups there are differences, if the export of Europe and the United States the rest, are certainly through the bleaching.
Black pearls with black and purple the best penetration. Overtone (usually rose red or green) is just like the rouge on ladies face , is fixed  above their own skin color.
 Not all pearls are presented Overtone. The third is the most rare pigment, that is the kind of crystal glossy color (Orient) ─ ─
that is presented to the surface of the kind of pearl iridescence. Not all pearls are showing such a crystal gloss, in fact, rarely rounded pearls have such shiny.
It is present in the irregular shape of the majority of above.

luster
luster is one of the important factors customer should  consider, it is decided by the from quality of pearl itself, transparency and the layer thickness of mother of pearl.Sometimes appears pale ring on the pearl waist, which is partially related to changes in crystal structure, should try to avoid such a bead.
There is no doubt that the stronger the luster, the better the quality.

layer thickness of Mother of pearl

the thicker, the better. layer thickness can be carefully observed from the Perforation of  the pearl beads , by the way observe whether the bead core was damaged when perforated .layer thickness can also be judged indirectly from the strength of pearl, beads which are too thin are not durable.ideal beads should be more than 0.5 mm. Cultured pearls sites (water temperature, nutrients, etc.) and aquaculture  time are the most important deciding factor of the layer thickness of pearl.

The shape
for the beaded pearls , should seek the  collections of rounded smooth, both said and rules. However, if you can buy larger pearls with less cost ,
it will be better.

flaw
In addition to obviously  out flaw , the flaw can also be cracked, crack, concave-shaped and dark or dull spots and the ring ,which should be avoided.
However, in larger observation,  always can find some problems.