A pearl is formed when a small irritant or parasite penetrates and lodges in the mantle tissue of a mollusc. In response, a substance called nacre is secreted, and the creation of a pearl begins. Nacre is a combination of crystalline and organic substances. The nacre builds ups in layers, as it surrounds the irritant, and after a few years, forms a pearl.

Natural pearls are formed by nature whereas cultured pearls have been given a helping hand by man. Today, nearly all pearls are cultured. Pearl farmers introduce a foreign object into a mollusc to induce the creation of a pearl. Cultured pearls can be designed to be much more consistent in shape, quality and colour than natural pearls so are perfect for jewellery.