Imitation pearls are manufactured to simulate both saltwater and freshwater pearls. They can be made from glass, plastic, wax, or shell, and coated with various products to mimic the appearance of natural and cultured pearls. 

The tooth test. Gently rub the bead across the biting edge of your front teeth. Imitation pearls will feel smooth; natural and cultured pearls feel gritty. Caution: coated natural and cultured pearls can also feel smooth. 

Examine the surface using magnification. The texture of imitation pearls can look smooth and even when compared to cultured pearls.