Lady's Akoya Pearl Necklace. Pearl Size: 6-6.5mm. Necklace Length: 18 Inches Approximately a half a century ago, Dr. Mikimoto, a japanese scientist, discovered the secret of growing cultured pearls. It is done with the help of a small ball fashioned from the shell of a Mississippi Mollusk. When a foreign object is inserted into an akoya oyster, such as this ball, the oyster secretes nacre and voila, a pearl was born. The same process is being used in pearl farms all over the world, but Mikimoto did it first.