The Culturing Stage of a Saltwater Pearl
After oysters are nucleated approximately 70% retain the nucleus after 30-40 days. The process of coating the nucleus begins with 10-20 layers a day! Other oysters won't survive disease and predators and that would leave about 50% of the oysters to grow pearls to harvest stage.
Usually pearls are harvested 18-24 months after being nucleated. The oysters are arduously cleaned and monitored every 3-4 months. So, only 50% of the harvested pearls will be of commercial value. Maybe 5% would be considered perfect. Because of so many variables, minerals, temperature of the water, movement of the oysters, and the food, each pearl will have a different size, shape, and color.
If an oyster produces an exceptional pearl, it may be grafted with another nucleus into the same pearl sac. An oyster can be nucleated up to 3 times. At this point the oyster would be 9 years old and deservedly ready for retirement.