The Difference Between Saltwater and Freshwater Pearls

April 13, 2011

At The Pearl Girls we absolutely love freshwater pearls. Although we use some saltwater pearls in our pieces, we adore freshwater because they are the closest rival to natural pearls. However, we’ve found that some people misunderstand freshwater pearls. After Mikimoto started culturing saltwater pearls in the early 1900s, he tried the same process in freshwater, yet he could not produce gem quality pearls! The freshwater pearls looked like pieces of rice. So, the name freshwater pearls became synonymous with off sized, lower quality pearls. How times have changed!

World War II halted the efforts to culture freshwater pearls in Japan and led to the Chinese taking over perfecting this process. They have come leaps and bounds in the past decades producing large, beautiful and round freshwater pearls. So, what is the difference in freshwater and saltwater pearls? To answer this, we turn to “Pearls:  A Natural History” which was a huge exhibit on pearls at the American Museum of Natural History. Unfortunately, this exhibit is no longer available, but the book from the exhibit remains a valuable resource.

Although the composition of pearls remains the same, there are five differences in the process of culturing freshwater pearls versus culturing saltwater pearls. First, to get the freshwater mussels, their larvae must survive. This is a difficult process because the larvae attach to a fish host before they metamorphose.  So, survival of the mollusk becomes an issue of culturing fish as well as the mussels used for pearls.

Inside the saltwater oyster or the freshwater mussel, the placement of the nucleus is different. In saltwater pearls, a bead or shell is inserted in the gonad of the oyster. This is not possible in freshwater mollusks because of its different composition. In freshwater mollusks a small piece of tissue is placed in the soft mantle tissue, which lines the shell. A piece of shell would never fit in this thin lining, so a piece of tissue is used instead. This leads to our third difference.

I have said before that freshwater pearls are the closest rivals to natural pearls. Because the nucleus is just a piece of tissue, these tissue-nucleated freshwater pearls are 100% nacre and are difficult to distinguish from natural pearls which have no nucleus at all. They are all pearl and tend to be heavier than their saltwater counterparts.

Freshwater pearls can be nucleated many times, meaning that the yield from a freshwater mollusk is higher than that of a saltwater oyster.

Freshwater environments are also easier to maintain than saltwater environments. In the ocean there tend to be more pollutants, which harm the pearl production.  Saltwater pearl farms must expend a lot of energy to clean their oysters both before and after nucleation.

Finally, saltwater pearl productions cost more money than freshwater. Saltwater farms require divers, ships, boats and complex equipment to access and maintain their saltwater pearl oysters. Freshwater farms are able to maintain their productions on a smaller scale. The total cost put into producing a saltwater pearl is considerable higher that what it takes to produce a freshwater pearl.

I hope this helps you understand the differences in these pearl processes. Let us know if you have any questions!


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