E ach year, millions of oysters are nucleated. But only a very small proportion live to bear fine quality cultured pearls. Too much depends upon the whims of unpredictable Mother Nature. Many of the oysters do not survive the surgical nucleating operation. Others are weak and susceptible to disease.
Heavy rains can flood the bays with fresh water, reducing salinity and killing the oysters.
Sometimes, certain species of plankton undergo explosive growth, creating the dreaded red tide that exhausts oxygen in a bay and suffocates the oysters. Then there are typhoons, attacks of predators and parasites, or lack of sufficient nutrients in the water. On the average, about fifty percent of the nucleated oysters do not survive to bear pearls. And only twenty percent bear marketable pearls. The rest are too imperfect, too flawed to be used as jewels.