Baroque pearls are simply pearls that have an irregular shape. Cultured freshwater pearls are most commonly baroque, because freshwater pearls are mantle-tissue nucleated instead of bead nucleated. Thus these pearls are rarely perfectly spherical and can appear oval or ovoid.
Akoya pearls (commonly known as cultured saltwater pearls) can also be baroque, but the baroque shape of an akoya pearl differs from that of a freshwater pearl. This is because akoya pearls are bead-nucleated; they have a perfectly spherical bead within. So in the event that a harvested akoya pearl turns out to be baroque, it has a small tail that comes to a sharp point behind a rounded front, in other words, it is teardrop-shaped.
The most valuable of baroque pearls are the South Sea and Tahitian pearls. These pearls are produced by the Pinctada margaritifera, and the Pinctada maxima (black-lipped oysters, gold-lipped and white-lipped oysters). Although these are a variety of cultured saltwater pearls, the amount of time that the pearls are cultured dramatically increases the depth of the nacre, and the likelihood of producing a baroque pearl. Most Tahitian pearl farm harvests, for example, produce more than 40 percent baroque and semi-baroque pearls. Western Australia is currently the worlds largest cultivator of Pinctada maxima gold lipped oysters. Tahiti is the number one cultivator of Pinctada maxima black lipped oysters.