How are brown pearls and other colors manufactured or created?

Answer There are several ways in which processors can change the color of a natural or cultured pearl. Aniline and Organic Dyes

Dyes are used which permeate the outer layers of a pearl and change its color. Irradiation

Cobalt-60, the safe daughter element of Nickel, is used to alter the manganese content of freshwater mussel shell. This is used to darken the nacre of freshwater pearls and darken the nucleus (which is composed of freshwater mussel shell) of akoya pearls. The Chocolates

Chocolate pearls are created either by an organic dye (in the case of freshwater and some Tahitian pearls) or by a proprietary process of heat treatment.