Establish a price range that you would like to spend.
Decide on the type of pearls that you want. There are four kinds: Akoya, Freshwater, South Sea and Tahitian. Each pearl type is unique in color, size, shape, and price. South Sea is the most expensive and freshwater is the cheapest.

Decide on the size of pearls that you want. Generally speaking, the larger the more expensive. Each pearl type has a different average size. Pearls range in size from 4mm-15mm.

Decide on the length of pearl necklace that you want. There are six typical lengths: collar, choker, princess, matinee, opera and rope. Collar is 10 to 13 inches in length. Choker is 16 to 18 inches. Princess is 17 to 20 inches. Matinee is 20 to 24 inches. Opera is 28 to 34 inches. Rope is 45 inches and up.

Finally, decide on the color, shape and quality that you would like that meets your price range. The color and luster are the two most important qualities that you should pay careful attention to. There are various grading systems such as GIA's excellent or AAA, and all reputable jewelers should have a consistent grading system for pearl necklaces over $5000.

By now, you should have a price range, pearl type, size, quality, and length of necklace determined. With this in mind, you can feel confident going to multiple jewelers to shop around and find the best value for you.