Pearls are among the most timeless and classic of all gems. Throughout history, they have been associated with wisdom, wealth, purity, and romance. Natural pearls start out as a grain of sand or another microscopic particle that settles inside an oyster. The oyster’s natural defense mechanism against this invader is to secret a smooth, hard substance called nacre. When layers and layers of nacre build upon each other, they harden to ultimately form a pearl. Do all pearl strands look the same to you and leave you wondering why some are so much more expensive than others? You’re not alone; they look the same to many people. But there are many different kinds of pearls with different characteristics that determine their values. Read on to learn about the factors that determine a pearl’s value and the different kinds of pearls and strands, and you’ll be sure to know how to pick the perfect one for you.

Five factors determine a pearl’s value. These include luster (surface brilliance; thicker nacre = better luster), surface quality (absence of bumps, cracks, or spots), shape (rounder = higher value), color, and size (average is 7–7.5 millimeters). Higher-quality strands will be comprised of pearls that weigh in on the favorable end of each characteristic. The International Gemological Institute (IGI) grades pearls, and their reports list all factors pertinent to a pearl’s quality. Reports include a description of any pearls contained in the article of jewelry, including a breakdown of pearl variety, size, shape, weight, body color and overtone, luster, surface quality, nacre thickness, matching, treatment (if applicable), and growth environment. By comparing reports, you can see the differences in a strand’s characteristics and find out exactly what you’ll be paying for.

Pearl strands commonly come in five lengths. The choker length is 16 inches and works well with most necklines and any style from casual to formal. The princess strand is 18 inches long, falling just below the neckline, and is perfect for professional wear, as it will fall above the neckline of most blouses. The matinee length is 20 inches long and great for formal occasions. Falling just above the bust line, this length is the right choice for anyone looking to show off the neck, shoulder, and chest region. Opera length is 32 inches long, and a good choice for formal and casual wear alike. Worn long, it compliments any body type, but it can also be doubled and worn as a double-choker length for more casual occasions. Finally, there is the rope length at 46 inches long. It will fall just about the waistline and offers a lot of versatility. From doubling to tripling the strand over, to simply knotting it and wearing it long, this is a classic length that offers many options.

Some of the different types of pearls. First, there are natural pearls, and there are cultured pearls; most pearls these days are cultured, which means they are partially man-made. Two different ways to create a cultured pearl are bead nucleation and tissue activation. Bead nucleation starts with a large bead inserted into the oyster, which then becomes covered in a thin shell of nacre, while tissue-activation pearls contain no bead and are closer in quality to natural pearls. Akoya pearls are classic round pearls grown off the coast of Japan and come in a range of colors. However, these cultured pearls are bead nucleated and tend to have a thinner shell of nacre, which can lead to flaking with wear. White South Sea pearls are grown in the South Pacific and tend to be larger in size. Chinese freshwater pearls are cultured, using the tissue activation method, which makes them a sturdier pearl. In natural or white, these pearls can be of the finest quality at a reasonable price. However, many are of lower quality, especially if they are treated to be different colors, irregularly shaped, or lacking in luster. Tahitian pearls, grown in French Polynesia, can grow to be quite large and come in a wide range of natural colors from gray and black to green and purple. These tend to be more expensive because of their uniqueness.

Choosing your strand. To determine whether all the pearls in a strand are round, hold the strand taut between two hands and rotate the strand. If there are irregularly shaped pearls in the strand, they will seem to jump out. If all the pearls are round, there will be no such movement. Oddly shaped strands of pearls should not be completely discounted, however. They often work well with a more casual look and usually cost less. Pearl strands come in many colors. Whichever color you like best, be sure to check it against your skin tone; just because it looks great in the jeweler’s case does not mean it will look great against your skin. If you want a quick look, hold the strand up to the inside of your wrist. The skin here closely resembles the skin color around your neck. But if you can give the strand a “test drive” and put it on, that’s even better!

Remember to take care of your pearls. Pearls are soft and require special care. Natural oils from your skin as well as many cosmetic products can make them dull. To clean them, use a soft damp cloth, and then store them separately in a cotton bag to prevent scratches. If you wear your pearls often, consider bringing them to a jeweler once a year for professional cleaning and restringing to prevent the strand from breaking.

Happy pearl shopping!