Imitation or Simulation Pearls
Imitation peals are also made as not everyone can afford to display a string or two of natural pearls around their neck.
There are basically 3 types of imitation or simulated pearls. Shell, glass and plastic.
Shell is probably the best of the three and the more expensive of course. Shell pearls are made from fish scales and oil called hemage (pronounced her'ma'ghee). This is made up into a paste which is applied usually in 29 successive layers to a base. The more layers applied the better the quality and the more expensive simulated pearls you will get. Each time a layer is applied it is allowed to dry and is polished to remove any imperfections before the next layer is applied.
The fine quality Majorca Pearls are an example of the shell pearl where this process is used but the actual details of the process are a closely guarded secret.
Glass Pearls is similarly made but the bas is a milky glass bead and sprayed or covered with hemage one to three times only then dried. The quality is considerably less than the shell pearl and the difference can be easily seen.
Plastic Pearls are simply a plastic bead painted or coated in paint to resemble a pearl and is the cheapest of the imitation pearls. The paint tends to peel off and so is not of much use to anyone.