Akoyas, of course, exhibit the traditional white, silver, or cream colors, while Tahitians and South Sea pearls yield necklaces of darker tones. Freshwater pearls can be either white or dark, and are generally more affordable than the saltwater options.
Pearl necklaces come in a wide variety of styles:
Bib: Consists of several strands of pearls of varying lengths. Collar or Dog Collar: Consists of multiple strands of pearls worn high on the neck. Very popular during the Victorian era, making a bit of a comeback now. 12-13 inches long. Choker: Similar to a collar, but is worn somewhat lower on the neck. 14-16 inches long. Princess: Essentially the "classic" length for a pearl necklace, lying slightly below the neck. A versatile style, which can be worn with many different styles of neckline. 17-19 inches long. Matinee: Traditionally worn for semi-formal occasions, works well with suits and dresses. 20-24 inches long. Opera: Generally worn at formal occasions with evening dresses. The pearls should fall below the bust line. To be worn during the day in less-formal settings, the strand can be doubled over. 30-36 inches long. Rope: This is the longest of all pearl necklace styles. It can also be doubled, as well as knotted. Some rope necklaces have multiple clasps, which allow it to be broken down into shorter strands. Over 36 inches long.
The pearls used in a necklace can all be of the same size; or they can be graduated, with a larger pearl in the center and successively smaller pearls running back on each side to the clasp. Whichever style is chosen, good matching of the pearls is important, both for aesthetic reasons and for the highest value.
The size of the pearls in the necklace, while ultimately a matter of personal taste, is also a subject of tradition. Traditionally, certain pearl sizes are considered appropriate for women of various ages; and the size of the pearls is also considered an indicator of the wearer's wealth and social status.
Smaller pearls (5.5-6.5 millimeters) are generally appropriate for teenage girls and younger women -- say, up to the mid-20s.
Pearls 6.5-8.0 millimeters are traditionally worn by women in the range of the mid-20s to mid-30s. They show a woman who, in a sense, has "come of age," but the pearls still remain modest and not too showy.
Pearls 8.0-9.0 millimeters in size definitely exhibit an aura of status, class, and success. They are traditionally worn by women in their mid-30s to mid-40s. These pearls tend to be more expensive (particularly the larger end of this scale -- 8.5-9.0 millimeters), and so are associated with financial success.
Pearls 9.0-10.0 millimeters are both rare and expensive. They are generally worn by wealthy women of more mature years.