Shapes that are not spherical or even symmetrical are considered lower quality. Akoya, Tahitian, and South Sea pearls found in jewelry have a tendency to be the roundest, while Freshwater pearls can be oval or slightly off-round.
Traditionally, the most desired pearl shape has been round. But nowadays, you can have pearls in as great a variety of shapes as you can colors.
Chinese farmers usually get two production cycles out of their pearl-growing mussels. During the first cycle, lasting about two years, the focus is on round pearls. If harvested pearls are put back in the water for another two year cycle, empty pearl sacks start generating second-growth free-form pearls of their own accord. Called “petal pearls” because of their flower petal shapes these pearls have found popularity with consumers looking for more individualistic pearls. So have black and white spontaneous-growth saltwater equivalents called “keshi” from Tahiti, Indonesia and Australia.
All in all, the emergence of China as the world’s leading pearl producer (95%+) has brought unprecedented pearl diversity. Indeed, it is safe to say that the pearl as a gem species has been reinvented.
A pearl’s color is also called the body color. The most prominent pearl colors are white, cream, yellow, pink, silver, or black. A pearl can also have a hint of secondary color, or overtone, which is seen when light reflects off the pearl surface. For example, a pearl strand may appear white, but when examined more closely, a pink overtone may become apparent.
While white, and more recently black, saltwater pearls are by far the most popular, other color tints can be found on pearls from the oceans. Pink, blue, champagne, green, black and even purple saltwater pearls can be encountered, but to collect enough pearls to form a complete string of the same size and same shade can take years.