"Chocolate Pearls" is the suggestive trade name for cultured pearls with a brown body color. 

I have these 13-13.5mm Chocolate Pearls if you desire something that I could. make for you.

In around 2004, brown-colored pearls were reported on the markets in an unusual scale compared to the few known brown Tahitian cultured pearls from French Polynesia. It happens that the color was caused by a new treatment patented by a New York company, Ballerina Pearl Co.. The treatment was carried out in Tahitian cultured pearls and involved bleaching (the use of chemical solutions and/or light to alter color).
These "chocolate pearls" became very popular even with its high price tag due the high cost of the starting material, if of good quality. This popularity lead to the development for alternative treatment methods at a lesser expense and many chocolate pearls have since then have been produced not only by beaching but also by dying (e.g. with silver nitrate).
More recently, natural colored chocolate pearls became known in Fiji, popular for its earthy-colored pearls.

Many thanks to Rui Galopim de Carvalho for this information.