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C. 
A cultured pearl undergoes the same process. There is only one difference between cultured pearls 
and natural ones: in cultured pearls, the irritant is a head called ‘mother of pearl’ and is placed in the oyster 
through surgical implantation. This results in much larger cores in cultivated pearls than those in natural 
pearls. As long as there are enough layers of nacre (the secreted fluid covering the irritant) to create a 
gorgeous, gem-quality pearl; the size of the nucleus wouldn’t make a difference to beauty or durability. 
 
D. 
Pearls can come from both salt and freshwater sources. Typically, pearls from salt water usually 
have high quality, although several freshwater pearls are considered high in quality, too. In addition, 
freshwater pearls often have irregular shapes, with a puffed rice appearance. Nevertheless, it is the 
individual merits that determine the pearl’s value more than the sources of pearls. Saltwater pearl oysters are 
usually cultivated in protected lagoons or volcanic atolls, while most freshwater cultured pearls sold today 
come from China. There are a number of options for producing cultured pearls: use fresh water or sea water 
shells, transplant the graft into the mantle or into the gonad, add a spherical bead or do it nonbeaded. 
 
E. 
No matter which method is used to get pearls, the process usually takes several years. Mussels 
must reach a mature age, which may take up almost three years, and then be transplanted an irritant. When 
the irritant is put in place, it takes approximately another three years for a pearl to reach its full size. 
Sometimes, the irritant may be rejected. As a result, the pearl may be seriously deformed, or the oyster may 
directly die from such numerous complications as diseases. At the end of a 5- to 10-year circle, only half of 
the oysters may have made it through. Among the pearls that are actually produced in the end, only about 
5% of them will be high-quality enough for the jewellery makers.