Pearls are unique gemstones that form naturally in mollusks and oysters. They arise when a foreign object, such as a grain of sand, enters the shell. To protect itself, the animal encapsulates the irritation with layers of nacre, which over time forms a pearl. Pearls have been used in jewellery for thousands of years and have often symbolised beauty, wealth, and purity. They come in various colours, such as white, pink, black, and gold, depending on the type of mollusk or oyster that created them. There are both natural pearls and cultured pearls. Today, most pearls on the market are cultured, meaning that humans assist the process by inserting an object into the mollusk. Despite this, pearls maintain their popularity and are considered timeless jewellery suitable for many different occasions.