These days you can buy pearl necklaces in all lengths, from short collar necklaces to long traditional strands of pearl necklaces. The most common length for pearl necklaces is around 18 inches. These necklaces go well with high-neck dresses and even crew necks. Long strands of pearls are also another popular choice. These are normally greater than 42 inches and are great for fancy dress parties or even dressing up an old office blouse.