Pearls come in a wide variety of colors, ranging from white all the way to black. The natural color of a pearl results from a combination of several factors:

Body Color The predominant basic color of the pearl.
Overtone The one or more colors that overlie the body color. On black pearls these colors are usually easiest to see in the lighter areas of the pearl. On white pearls they are easier to see in the darker areas.
Iridescence A play of lustrous colors. They may be like those of the rainbow, or they may be a subtle combination of colors such as pink, blue, green and silver. The colors of the pearls change when you move them in your hand.

 
Pearl color does affect the price of pearls. This affection is more prominent on saltwater pearl than on freshwater pearl. It differs from type to type. Even pearls in a same category have quite different price level just because of their color. The presence of overtone color and iridescence can make pearl more valuable. However, pearl jewelry is a decoration to inspire beauty of wearer. It is better to choose suitable one instead of precious one. Your primary concern should be what looks best on you.
 Surface imperfections to avoid when choosing pearls
1. Judge the color of pearls against a non-reflective white background. Pearls not only reflect the color of the background, they also absorb it. Afterwards, place the pearls on your hand or around your neck to see how they look on you.

2. Take into consideration the lighting. If possible look at the pearls under different types of light sources-daylight near a window, fluorescent, and incandescent (light bulbs). You'll probably be wearing the pearls under a variety of light sources.

3. it’s a lot easier to compare color than to remember it. If possible, wear or take along some comparison pearls. Otherwise, compare the color to other pearls in the store. Even using white and cream-colored papers as color references is better than relying on color memory.

4. When pearl strands are exactly adjacent, their color may seem to bleed from one strand to another. Therefore, also compare them slightly separated from each other.

5. Every now and then, look away from the pearls at other colors and objects. When you focus on one color too long, your perception of it becomes distorted.

6. Consider how evenly distributed the color is on the pearls, especially if it's one major pearl on a ring or pendant. A uniform color is more highly valued than a blotchy one.

7. If you are trying to decide between white and pink pearls of the same quality but the pink pearls cost more. Look in a few of the drill holes with a 10-power magnifier. If you can see red or pink stains on the nacre layer or a pink line between the nacre and the nucleus, they are dyed. Seeing positive indications of dye may influence your decision. By the way, even if you don't see evidence of dye, the pearls may still be dyed.