It seems as though pearls are available in every color under the sun, so why is it that purple, the color of mystery, magic, intrigue, and royalty, is so rare? Try looking for a purple pearl necklace and see how many you can find; the truth is that this color is not only rare, but can be expensive depending on which type of pearl it is. This is because there are only two types of purple pearls in the world, one naturally occurring, one not. Let me explain.
Freshwater pearls can be lavender, but tend to be more on the pink side. A plus: lavender is a natural color. However, if you'd like a deeper shade of purple then dye is the only option. Freshwater pearls can be dyed very easily, and because they are easily mass produced, you won't have to spend as much to find great quality. On the downside, many of the pearls that are dyed are lower quality, so be on the lookout for possible blemishes or surface flaws if you have the opportunity to see your pearls before you buy them.
The other type of pearl comes from the Quahog clam - that's right, a clam! This clam has a beautiful purple shell, and so the pearls that it forms are purple also. In fact, this was the same type of clam that used to be formed into wampum, a type of currency used by Native Americans centuries ago. If you're very lucky, you may find a Quahog pearl while eating, but otherwise they are extremely rare. Not only do these clams not form pearls very often, but the recent mechanization of the harvesting process means that any existing pearls are just as likely to be discarded. If you find one of these lovely pearls, the best way to wear it is in a bottle on a chain - they are very fragile and don't take to drilling very well. This also means that they are difficult to sell, so you won't see very many on the market.
If you truly want purple pearls, you'll be able to find them but it may not be easy. Freshwater pearls are all over the place and can be a great value for the money provided you inspect them for flaws and make sure they have decent luster. However, if you're looking for Quahog pearls, you may spend years searching unless you go to a dealer and make your request clear. Getting a pearl necklace made out of them is nearly impossible though! Either way, the end result is sure to be fantastic.