A pearl is formed when an oyster reacts to an intruder invading its shell. As a defense mechanism, the oyster produces a substance known as nacre that forms layers around the intruder, creating a pearl as a result. The timeless beauty of a pearl necklace is unrivaled. Here are some pearl necklace buying tips to help you add class, elegance and flexibility to your wardrobe. When you’re choosing a pearl necklace, it is important to know the basics of pearls. There are naturally produced pearls, cultured pearls and synthetic pearls. These range from the highest in value to the lowest (in that order). Because natural pearls are rare, cultured pearls are a popular choice as it is very difficult to tell a natural pearl from a cultured one. Pearls can be formed in saltwater or in freshwater with saltwater versions being more expensive. With 3 different shapes, symmetrical, round and baroque, you can find a pearl necklace to suit any style and physical body type. A commonly chosen shape is the round or spherical pearl. Irregularly shaped pearls are classed as baroque and can look like sticks or crosses, for example. Symmetrical pearls come in oval, button and drop shapes. Important pearl necklace buying tips lie in choosing the right length for the wearer’s neck length and shape, age and overall physique. In general, a long necklace will elongate the neck while a shorter necklace will flatter longer necks. A pearl necklace can come in a range of lengths from the longest rope length (at least 37″) to the shortest: collar (10″ - 13″). A pearl necklace of between 18″ to 24″ will generally suit everyone. The collar pearl necklace is worn high and above the base of the neck, and is suited for evening and casual use. Chokers, on the other hand are 16 to 18 inches long and worn around the neck’s base. The princess is a very popular length (17″ to 20″) and can be worn with any type of neckline. If you’re choosing a pearl necklace to wear with corporate or business outfits, or for semi-formal events, then the matinee length is ideal. The rule-of-thumb goes that people with short necks should wear necklaces that sit at least 2 inches below the collarbone while people with longer necks should wear necklaces that sit at the base of the neck.