There are four main types of cultured pearls, which are determined both by the type of mollusk a pearl is grown in, as well as where it is grown. These four pearl types are:
- Akoya Pearls
- Tahitian Pearls
- South Sea Pearls
- Freshwater Pearls
Both the type of mollusk a pearl is grown in and the surrounding environmental conditions (nature and nurture!) will have an impact on the resulting pearl and its size, shape, color, luster, nacre quality/thickness, and overtone. These characteristics determine a pearl’s quality and value. Additionally, supply and demand factors also play a role in determining a pearl’s value – as an example, a single freshwater mussel can produce 20-30 pearls vs. an Akoya oyster that produces only one, and as such Akoya saltwater pearls tend to be valued more highly than comparable quality freshwater pearls.
Akoya saltwater pearls are what most people think of when they think of cultured pearls. Akoya pearls are often perfectly round, white (or white with a pink overtone), typically 6-8mm and exhibit extremely high luster. The Akoya saltwater pearls were famously first cultured by Mikimoto in the late 1800’s in Japan, and Japan remains the dominant source of Akoya pearl production today. The reflective, sharp luster of Akoya pearls tends to be their defining characteristic, and is due to the colder waters of Southern Japan where (because colder waters produce higher luster, pearls in other regions tend to be harvested in the colder months, so that the last few layers of nacre exhibit the highest luster possible).
Tahitian pearls are grown in the pristine waters surrounding Tahiti / French Polynesia in the Pinctada Margaritifera mollusk. While colder waters produce high luster pearls, pearls grown in warmer climates grow much more quickly. As a result, Tahitian pearls can range from 8mm to as large as 18mm, both due to the warmer temperatures and large size of the Pinctada Margaritifera. The Pinctada Margaritifera mollusk itself often grows to about 12 inches across - the size of a dinner plate (and in fact the shells can be turned into decorative dinner plate chargers).
The Pinctada Margaritifera mollusk is commonly referred to as the “black-lipped oyster”, and Tahitian pearls may also be referred to as “black pearls” though in fact a truly black pearl is very rare (and valuable) indeed. Most Tahitian pearls are actually charcoal or grey in body color, and then often have rich overtones ranging from silver, to blue and green (peacock), to pink and lavender (aubergine). Tahitian pearls come in a variety of shapes. Baroque or oblong shapes are most common, with perfectly round Tahitian pearls being very rare.
South Sea Pearls
South Sea pearls are grown in the large and spectacular Pinctada Maxima mollusk, typically in the waters off the coast of Western Australia. Pearl farming in this region is limited by regulation, which protects the wild stock of these oysters, ensures the quality of farming methods and the pearls produced, and keeps the value of South Sea Pearls high due to their limited supply.
South Sea Pearls are typically large (ranging from 8mm to 22mm) and have a very soft, satiny luster due to the warmer water temperatures where they are grown. South Sea Pearls range in color from white and cream to extraordinary golden hues. Golden South Sea pearls are among the rarest and most sought-after pearls in the world. Due to their scarcity, Golden South Sea pearls tend to be one of the most expensive pearl varieties, and as such are most often found in pendant necklaces, earrings or rings. A full strand of Golden South Sea pearls is both extremely rare and expensive – but makes for a truly luxurious and exceptional piece of jewelry.
The development of freshwater pearl culturing techniques occurred after the saltwater pearl culturing industry was fully established, and as such, early results of freshwater pearl cultivation gave many a poor impression of freshwater pearls, which were often produced in “rice-krispie” shapes and yellowish hues that were not particularly attractive. This changed in the late 1990’s and today, freshwater pearls can rival Akoya saltwater pearls across many value characteristics (though intensity of luster is one characteristic where Akoya pearls tend to reign).
The industry did develop in Japan in Lake Biwa, but unfortunately due to environmental pollution, most of freshwater pearl production has moved to the lakes and rivers surrounding Shanghai, China. The Hyriopsis Cumingli mollusk, commonly referred to as a triangle mussel due to the shape of its shell, is most often used. As mentioned, a single mollusk can produce as many as 20-30 freshwater pearls. The total annual production of Chinese freshwater pearls has been estimated to be over 1500 tons, and while only ~2% of freshwater pearls are perfectly round, 2% of 1500 tons is still a very large amount! Freshwater pearls are often baroque (oblong), button (flat on the bottom, round on top), coin-shaped, or other irregular shapes. These various shapes of freshwater pearls typically range in size from 6mm to 10mm, and can make for very unique and interesting pieces of jewelry.
Finally, in terms of color, freshwater pearls come in the widest range of hues – from whites and creams, to yellows, peaches, pinks and lavenders, and even some lighter green and blue hues. These colors are produced naturally but do tend to be lighter, pastel colors; if you see freshwater pearls in lime green, electric blue, royal purple, fuschia or red, they almost certainly have been dyed or treated (and the dealer or jewelry retailer should disclose them as such). At OOpearls.com, we focus on only the highest quality (round or near-round) freshwater pearls, and offer a range of these beautiful colors.
We are often asked: “What is the difference between cultured and natural pearls?” Natural pearls are pearls that develop without human intervention. Before the culturing industry developed in the late 1800’s/early 1900’s, natural pearls were all that were available. An entire industry of pearl diving existed, centered in the Persian Gulf, where at great peril, pearl divers would search for natural pearls.
After pearl culturing methods became consistently able to produce high quality pearls, through the process of inserting a bead nuclei into a pearl-producing mussel, the market for natural pearls collapsed. Today, natural pearls are both very rare and valuable.