Imitation pearls date back to antiquity, but were only mass-produced from the 16th and 17th centuries in Italy and France. They are, as the name suggests, entirely man-made. Imitation pearls in days gone by used a shell bead as a nucleus, covered by a coating of fish scales.

Today, more modern laboratory techniques are employed. Nuclei are made from either shell material, plastic, glass or porcelain. New synthetic materials, combined with sophisticated coating techniques, produce an imitation pearl that may often be mistaken, at first glance, for either a natural or a cultured pearl.

The most famous name in imitation pearls is "Mallorca" (or "Majorca"), from the Mediterranean island off the Spanish coast. There are many other production centers throughout the world, mostly concentrated in the Far East.

To differentiate an imitation pearl from either a natural or cultured pearl, experts employ a variety of methods such as measuring fluorescence under ultraviolet light, analyzing specific gravity or examining the surface by means of an electron microscope.

An easier method is to "bite" the pearl. Rub it gently between your front teeth. If the surface feels "sandy" it is likely to be a natural or cultured pearl. If it feels smooth and glossy, it is likely to be an imitation pearl.