Fakes include glass and plastic beads, and mother of pearl beads, coated with ground mother of pearl. Also there are some fake pearls that are made from the solid part of the shell and sold as “pearls”.
-the best known way to tell a genuine pearl from an imitation pearl is to rub the pearl across the front of your teeth. A genuine pearl will feel gritty. An imitation pearl will feel smooth. Not completely reliable, this test has been used for years.
-similar to the tooth test, rub two pearls together. They will feel gritty. Glass or plastic will feel smooth.
-Magnification will show the edges of the drilled holes, and that they are drilled pearls or not. The surface of the genuine pearl will look under magnification to be irregular and rough, compared to the “perfect” machine made bead. A lot of what makes a pearl identifiable is that it is not “perfect” it has irregularities.
-X-rays can show a nucleus in a cultured pearl. All pearls that are cultured have this bead inside that is visible when x-rayed. Generally Freshwater Pearls and natural pearls are not bead nucleated, and are solid nacre.
-take athe pearl necklace into the sun. The sun with it’s full spectrum of light will show the irregularities such as color, overtones and surface. A real pearl necklace will show the pearls in one necklace to vary in color, shape etc. An imitation pearl necklace will look perfect, all seamlessly matching in color and size.
If you are buying from a reputable pearl jeweler, you will be unlikely to buy fakes. The current fake fad is Masami “pearls”. Made from a bead cut and rounded from a shell, they blatantly call them “pearls”. They are made from the discarded shells. They may be coated with a mixture of mother of pearl.