Cultured pearls grow around a nucleus that is manually inserted into an oyster or mussel. Modern techniques place the nucleus within the soft body of the oyster, away from the shell, allowing it to grow freely. Older techniques place the nucleus between the mantle and the shell of the oyster, where the pearl develops as a "blister" attached to the inner shell.

Blister pearls are left attached to the shell backing and the shell is polished to a smooth surface. Blister pearls are often cut into lovely freeform shapes, showing both the inner shell and the pearl. They can also be cut so that just the round pearl is left. These are in essence "half-pearls" and are often used in earrings, rings, and pins where a flat back is desirable.

Some people call blister pearls "mabe (ma-bay) pearls". This is only accurate if the blister pearl was grown in a Mabe oyster.

The Mabe oyster is a penquin wing oyster that produces blister pearls with better luster, iridescence, and color than other species. Mabe Blister Pearls have a rainbow spectrum of colors on their brilliant nacre, hence they are also called Rainbow Pearls.

Mabe pearl is also used to refer to the process of creating a half-pearl - even when the pearl was not grown in a Mabe oyster. These half-pearls are manufactured by a specific method - the cultured blister pearl is cut off the shell, the manually planted nucleus is extracted, the inside of the nacre coating is painted, the void left by the nucleus is filled with an epoxy, and the pearl is finished by covering the bottom with a polished piece of mother-of-pearl.