Say someone really liked strawberries, but could never find enough of them in the woods, or the ones they found were too small, or too tasteless? That person is glad that some intelligent folks figured out how to propagate strawberries and develop them into large, sweet, red gems that explode with flavor.
Cultured pearls happen much the same way...through planning, development and farming techniques.
My son planted strawberry seeds this year in a planter. Without the seeds, no strawberry plants would have sprouted.
Without a little help most mussels or oysters won't grow a pearl either.
But there are ways to "start a pearl" growing in these mollusks (or molluscs). (Mollusks are any of numerous chiefly marine invertebrates of the phylum Mollusca, typically having a soft unsegmented body, a mantle, and a protective calcareous shell and including the edible shellfish and the snails.)
Several people worked on figuring out to start a pearl growing, but Mikimoto is often the man credited with carrying the process to full development.
It's similar to taking a plant cutting. Has your mother ever visited a friend's garden who shared a "slip" of geranium with her so she could start her own plant?
Though this interesting website about pearl jewelry, you can find the highest quality custom freshwater pearl beads, freshwater pearl strands, freshwater pearl neckalce, freshwater pearl bracelet, freshwater pearl ring, freshwater pearl earrings, freshwater pearl pendant, sterling silver jewelry, single strand necklaces… online. Their designers and creators have been in the jewelry business are very special, and they always stayed in touch with the latest jewelry fashion trends the entire time.
Orignal From: Say someone really liked strawberries
A pearl starts growing when some irritating foreign substance such as a sand grain, bit of mud, parasite or other object becomes lodged in the shell-producing gland called the mantle. Pearls formed in the soft flesh where nacre can be added on all sides are most likely to be spherical and the most highly prized. By far the great majority are flattened or variously distorted and have little value. Size, color, luster and freedom from flaws are other essential qualities. Unlike other gems, such as diamonds, pearls have an average life of only about 50 years. In time the small amount of water in a pearl's make-up is lost and its surface cracks. Because they are mostly lime, necklaces which are worn often are injured by the acid secretions of the human skin. 
Natural or real pearls are made by oysters and other mollusks. Cultured pearls also are grown by mollusks, but with human intervention; that is, an irritant introduced into the shells causes a pearl to grow. Imitation pearls are man-made with glass, plastic, or organic materials. 
Always check the color. Yes it really depends on the preference of the buyer on what kind of color to get but as much as possible, try to not get the solid black pearls if you regard it as an investment. The more overtones a pearl has, the more valuable it is. Therefore choose a pearl that has blue, green, red, purple or pink overtones. 