There are a wide range of qualities, but it can be wildly divided into "Hanadama" which has an extremely strict criteria and the rest are classified as Akoya Pearls. Akoya Pearls are traditionally worn during Japanese Weddings and is used as an important item for ceremonial and formal occasions.
South Sea Pearls
The large South Sea Pearl shell lives in the depths of the ocean, and can produce pearls sized from 8mm to 20mm.
Their colors can range from white, silver white, pink white, yellow, and golden. South Sea Pearls generally take 2 years to produce, their characteristics are quite different to Akoya. They have many layers, and deep luster producing a long lasting beauty.
South Sea Pearls are distinguished by the color of the lip of the shell. Either a white/silver lip or a golden lip shell produces their individual colors. A silver/white lip shell can be found in Australina waters, and gold lip shells can be found in Indonesia, Philippine, and Myanmar waters. South Sea Pearls produce a unique beauty even being called the Mother of Jewels.
Tahitian Pearls are also considered South Sea pearls yet are almost exclusively produced in Tahiti (French Polynesia) most commonly in the Cook Islands. Tahitian Pearls range from 7mm to 18mm from a black lipped shell with a wide variety of colors.
However, the colors are all a tone or shade of black such as black green, black red, black gray, etc. A peacock green is the most revealed color with a reddish reflection and deep green just as a peacock's feathers.
Freshwater Pearls are cultivated in lakes and ponds and are produced in mussels.
Since Freshwater Pearls are not cultivated using a nuclear, it forms a wide variety of unique shapes. Most commonly, it comes in an oval shape yet rice, potato, drop, stick, and baroque shapes can be found.
The production can be found mainly within China, but Japan has successfully cultivated Freshwater Pearls as well.
Their colors come in white, purple, orange, pink, rose, and other pastel colors that cannot be found in any other shells.
Mabe Pearls is a semi round pearl made through inserting a semi round nuclear when cultivating. Mabe Pearls are predominately produced in Japan and have an incredibly high luster due to the special shell that Mabe is made from. The color comes in white, Champagne cream, bewitching green and metallic blue. Based on the nuclear, there are unique shapes that can be produced from drop, heart, marquis, and triangles.