How Are Pearls Made Naturally?

Natural pearls are made in mussels and oysters.

Natural pearls are pearls that are made without human intervention. Because of the rarity of natural pearls and the shrinking of natural mollusk beds due to pollution, natural pearls are extremely expensive. Most natural pearls on the market today are antique pearls.

Process

The first step in a pearl's creation is that a foreign object, usually a piece of bone or shell, enters a mussel or an oyster. To make this irritant less irritating, the mollusk secretes nacre. Nacre is a substance the mollusk uses to create its own shell. When you open any mussel or oyster, notice that the inside of the shell is luminescent and resembles the surface of a pearl. Nacre is made of calcium carbonate, which is highly reflective of light. Layers of the nacre build up over the irritant and and eventually the pearl is formed.

Time

Natural pearls that develop in the wild can take up to 10 years to grow to 6 mm. This is significantly longer than cultured pearls, which take two to four years to form. In the natural process, the longer a mollusk lives, the higher the chance that it will be carried off in a typhoon or eaten by a predator. This makes large natural pearls incredibly rare.

Quality

Natural pearls are more expensive than harvested pearls because in addition to being rare, they are higher in quality. Natural pearls are essentially made up entirely of nacre, while most cultured pearls are "seeded" with a bead. Poor quality cultured pearls may eventually wear down to show the bead underneath.

Rarity

Very few mollusks naturally carry pearls. Most mollusks are able to spit out any irritant, and only the irritants that are lodged deep in the mollusk eventually turn into pearls. Because of over-fishing, oil drilling and pollution, natural pearl beds are shrinking and mollusks often die before they can form a pearl.

Color

Pearl color can range from white to pink to green and black. Some breeds of oyster and mussels create unique colors, but diet, water temperature, and pollutants in the water are the main factors affecting the final color of the pearl. Black pearls are some of the most sought after pearls and can be found in French Polynesia, Indonesia, and the Philippines.

Freshwater vs. Saltwater

Freshwater pearls are made in mussels in rivers, and saltwater pearls are made in oysters in seawater. Saltwater pearls are round and are generally used to make rings, necklaces, or earrings. Freshwater pearls are misshapen and are used to make broaches or necklaces.

References

• PGA: Natural Pearls
• AMNH: What Are Pearls