- Natural pearls are formed when an irritant such as a grain of sand gets inside the hard shell of a soft-bodied mollusk. Nacre, a combination of crystalline and organic substances, is secreted to protect the mollusk's body. It builds up in layers and, after a few years, forms a teardrop-shape pearl with one flat side, known as a hemispherical mabe.
- Since natural pearls are rare--only one in 10,000 mollusks will produce a pearl--two late 19th-century Japanese researchers explored methods to artificially encourage the formation of pearls. In 1916, Kokichi Mikimoto patented a technique involving tissue and bead insertion into akoya mollusks that produced the first round pearls.
- Artificially induced pearls are known as cultured pearls. Natural pearls have varying qualities, shapes, colors and sizes, but high quality, round cultured pearls are designed as spherical from the beginning. The selection of cultured pearls includes freshwater, South Sea, Tahitian and akoya.
- Unlike naturally-colored pearls, chocolate pearls have an uncommon bronze, copper or rust-brown hue with strong iridescent overtones. Most chocolate pearls are created using a silver nitrate dyeing process.
- Ballerina Pearl Company and Shanghai Gems S.A. developed proprietary methods that modify and enhance a cultured pearl's melanin pigment color. No dyes or coloring agents are used to deliver the pearls' chocolate tone. Gemologists consider dyed chocolate pearls as "treated" pearls, resulting in a considerably lower selling price.
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