Originally Posted by Dmax
I know a bit about pearls...
Talking about cultured, commonly available ones there are four main types, determined by the type of mollusk they come from:
1. Freshwater pearls - Least expensive, commonly smaller than the other types of pearls, naturally come in lighter colors (white, pink, lavender,etc.), most darker colored ones are dyed. Off-round (aka baroque) shapes are common. More durable than other pearl types because they consist of solid nacre (the pearly substance giving the pearl its appearance). Freshwaters do not have the same depth of glossy finish found on other types of pearls.
IMHO, premium freshwater pearls are a good choice for an everyday necklace.
2. Akoya - generally larger (7-9mm common), shinier, and more expensive than Freshwater type. Nacre layer is thinner, because each oyster builts up a layer of nacre around a ball inserted into it. Akoya is what most people think of when they think of pearls. Untreated/undyed Akoya are mostly white and white with light color overtones.
A large percentage of Mikimoto pearls are super-premium Akoya. Super-Premium Akoyas are also available from other retailers as well as online.
3. Tahitian - larger than Akoya (9-12+mm common). Best known for their natural dark color with various mettalic overtones. The only type of pearls with naturally dark coloring. Somewhat thicker nacre than Akoya. More expensive than Akoya. Round and slightly off-round shapes common.
Average sized baroque necklace could be a good value compared to perfect round ones IMHO. Meryl Streep wears a gorgeous strand of huge baroque Tahitian pearls in some of her movies (The Manchurian Candidate, The Devil Wears Prada) which must have cost a fortune.
4. South Sea - the largest and most expensive pearls (13mm average). Most often encountered in lighter colors (gold, white, silver) having an incredible depth to their finish.
Pearl grading is not as standartized as diamond grading so when a particular retailer assigns a certain grade to some pearls it is mostly helpful in comparing them to other pearls this retailer sells but not to other retailers.
I would first like to say that the above is fantastic information, conveyed very well. I would like to add a little bit about the pricing of the different types of pearls, and note that they are not so easily comparable as the above would make them seem. With the different sizes between the different varieties of pearls, it is difficult to say which is more expensive between varieties as a blanket statement. For instance: A very large Akoya pearl (10mm or so) would cost more than a small South Sea Pearl of the same size (other factors being equal) because it takes longer, and is more difficult to produce an akoya pearl of that size.
I am a Graduate Gemologist working for a retail jewelry store in the Napa Valley, CA. I happen to have been a pearl wholesaler before I moved into the retail segment of the jewelry industry. I would be happy to put together some pricing and pictures for you if there is something that you are looking for. Because of my background, we have an excellent supply of pearls in our store.
Please PM me if you have questions or would like me to put together some information for you!
Hopefully I will have some time this afternoon, and I will post up a lot more pearl information for all of my fellow pearl lovers on the board!