They were rare because they were created only by chance. pearls bijoux can be in eight basic shapes: round, semi-round, button, drop, pear, oval, baroque, and circled. Perfectly round pearls bijoux are the rarest and most valuable shape to use as pearl and diamond bijoux. Semi-rounds are also used in pearl pendant necklaces bijoux or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. Button pearls bijoux are like a slightly flattened round pearl and can also make as pearl pendant necklaces bijoux, but are more often used in single pendants or pearl drop earrings where the back half of the pearl is covered by metal, making it look like a larger, and rounder pearl.

Today pearls bijoux are mostly cultured by people. Shell beads are placed inside an oyster and the oyster is putting back to the water. When the pearls bijoux are later harvested, the oyster has covered the bead with layers of nacre. Nowadays, most cultured pearls bijoux are produced in Japan at the warmer waters of the South Pacific, larger oysters produce at South Sea cultured pearls bijoux and Tahitian black cultured pearls bijoux, which are larger in size while freshwater pearls bijoux are cultured in mussels, mostly in China.

The quality of pearls bijoux is judged by the orient, which is the soft iridescence caused by the refraction of light by the layers of nacre, and luster, known as the reflectivity and shine of the surface. Among those attributes, luster is the most important differentiator of pearl quality according to jewelers. All factors being equal, however, the larger the pearl the more valuable it is. Large, perfectly round pearls bijoux are rare and highly valued. Fine pearls bijoux do not have any flaws or spots in the nacre which has an even, smooth texture. Other factors which affect value are the regularity of the shape, size, and color in which rose tints are the most favored.

Cultured and natural pearls bijoux can be distinguished from faux ones by a very simple test. Take the pearl and rub it gently against the edge of a tooth. Cultured and natural pearls bijoux will feel slightly rough, like fine sandpaper, because of the texture of natural nacre. Faux pearl will feel as smooth as glass because the surface is mounded or painted on a smooth bead.