are flat-bottomed, half-spherical Pearls that have grown attached to the inner shell of a mollusk
, rather than in the soft tissue, as is more common. Sometimes this can occur naturally. Some common mollusks that grow mabe pearls are the Pinctada Maxima
, Pteria penguin
and Pteria sterna
. They are harvested in New Zealand, Australia, Japan, China, Korea, the Philippines, Indonesia, French Polynesia, Mexico and the United States.
Cultured Mabe Pearls, also known as Blister Pearls when they are growing, have been grown by Pearl farmers on purpose since the 1970's, by attaching with glue a flat or hemispherical nucleus or disc to the inside of the shell. Besides using oysters, abalones are also used to produce Mabe Pearls.
Mabe Pearls can take various forms, as rounds, drops, ovals or hearts. Specialty shapes can also be created. These discs are covered with nacre
by the mollusk, over time, with layers building up and producing the characteristic pearly iridescence
and sheen. This can take between eight months and six years, at which time a millimeter or more of nacre will have built up over the glued-on disc. Mabe Pearls can be as small as five millimeters and as large as 20 millimeters, depending on the size of their mollusk host and the introduced hemispherical disc.
After harvesting the oyster, the Mabe is cut off the shell using a circle-bit or hollow core drill bit, and the disc removed. The hollow from the disc is then filled with a resin and backed with a flat piece of mother of pearl. Occasionally a bead is also used to fill the hollow. The resin can be dyed various colors. Coatings above the filler or below the inner dome of the blister Pearl can also be added, creating different illusions, especially when the added coating is reflective. This can enhance the luster and color of the Mabe Pearl.
These Mabe Pearls are most often used in applications like earrings and rings, where their flat shape is beneficial. They have good luster and orient, and a variety of colorations and shapes, but they are less expensive than round pearls that can be strung. They can range from pinks to blues, and rainbow colors with swirls.
Osmena Pearls are occasionally sold as Mabe Pearls, but are really carved pieces of the chambered nautilus shell, or turbo snail shells. Although beautiful, they cannot be truly called Mabe.