A pearl is a hard, glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as a conulariid. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has been deposited in concentric layers.
For nearly 100 years, akoya pearls grown off the coast of Japan have been the classic pearl of choice. When one pictures a round strand of white pearls, they are usually thinking of akoya. Although rare baroque shapes and natural colors like silver-blue and gold do exist, akoya pearls are best known for their perfectly round shape and sharp, reflective luster. While exceptions do exist, most akoya pearls produced today range in sizes from 4 to 10 mm. If you are looking for a classic strand of round, white pearls, you are probably looking for a strand of akoya pearls.
The most affordable pearls sold today, freshwater pearls are known for baroque shapes, white and pastel body colors and softer luster than akoya (except in the case of rare metallics). With natural pastel colors and shapes that range from perfectly round to free-form baroque, freshwater pearls offer a widest range of options. Common sizes range from 5 mm to 12 mm, but recent advances have led to the development of round and baroque pearls as large as 20 mm. If you are looking for an affordable piece or something more fashion-forward with unique combinations of colors and shapes, shop freshwater pearls.
Tahitian pearls grown in French Polynesia are the only naturally dark pearls. Although often referred to as black, Tahitian pearls come in a rainbow of exotic colors. Round Tahitian pearls are quite rare but other fun shapes like drops, baroques and ovals are highly-sought and still considered very valuable. When measured perpendicular to the drill hole, most Tahitians range in size from 8 mm to 15 mm regardless of shape. If you are looking for a naturally dark pearls that go well with almost any style, Tahitian pearls may be your best choice.
South Sea Pearls
Grown primarily in Australia the Philippines and Indonesia and ranging in color from white to gold, South Sea pearls are the largest saltwater pearls grown today. Because of their tremendous size, perfectly round South Sea pearls are quite rare. Other more common shapes are drops, baroques and ovals. All are considered very valuable. While South Sea pearls range in size from 8 mm to 18 mm, the most common sizes range from 10 mm to 14 mm. If you looking for the statement piece of jewelry with large pearls, South Sea may be the way to go.