Saltwater vs Freshwater Pearls: What's the Difference?

Saltwater and freshwater pearls are both cultured pearls, but they come from different animals. Saltwater pearls grow in pearl oysters, and freshwater pearls in mussels. The table compares the three main saltwater types with freshwater pearls, using the Learn About Pearls dataset.

How saltwater and freshwater pearls are grown#

Saltwater and freshwater pearls start differently. For a saltwater pearl, a technician implants a small piece of mantle tissue with a polished shell bead into the oyster’s gonad. For a freshwater pearl, a piece of mantle tissue alone does the same job, so no bead is needed.¹ Almost all freshwater pearls are grown this way.¹¹

The number of pearls differs too. Akoya and South Sea oysters grow one pearl at a time. Freshwater mussels grow their pearls in the mantle, where up to 20 grafts fit in each of the two mantle lobes, so a mussel usually yields more than 10 pearls.¹ CIBJO puts the usual number at 30 to 40 non-beaded pearls at a time.⁸

Mussels are also quicker to raise. Freshwater mussels are ready for pearl culture within a year, while pearl oyster larvae need at least a year and a half to grow to a size suitable for it.¹

Shape, size and color#

Saltwater cultured pearls generally follow the shape of the round bead inside them, so most are round or near-round.¹ Freshwater pearls grown from tissue alone often have irregular shapes, while bead-cultured freshwater pearls are often near-round to round.⁴

Freshwater pearls come in a remarkable range of sizes, shapes and colors.⁷ Among saltwater pearls, South Sea cultured pearls are the largest,¹⁵ and Tahitian pearls bring the dark colors.⁷

Output and price#

Freshwater pearls dominate by weight. From 2005 to 2014, China produced over 98% of the world’s cultured pearls by weight, 99.5% of them freshwater, but because freshwater pearls sell for much less, that output made up only about 5% of the world’s pearl value.¹ The world’s output of round saltwater pearls is far smaller, about 54 tonnes a year.¹

GIA calls freshwater cultured pearls the most affordable pearl type, and says Akoya cost more than freshwater pearls of similar size and quality, in part because they are rarer and cost more to culture.⁴

How labs tell saltwater and freshwater pearls apart#

The water a pearl grew in shows in its chemistry. Freshwater pearls contain more manganese and barium, and less sodium, magnesium and strontium, than saltwater pearls.² A GIA report states whether pearls grew in freshwater or saltwater, and which mollusk produced them when that can be determined.⁴

Names matter as well. CIBJO requires the full term “freshwater cultured pearl” for any pearl cultured in freshwater,³ and GIA calls names such as “freshwater Akoya” misleading.⁴

Choosing between saltwater and freshwater pearls#

Choose saltwater cultured pearls if you want the round shapes and mirror-like shine of Akoya, the size of South Sea pearls or the dark colors of Tahitian pearls.^{4 7}

Choose freshwater cultured pearls if you want a wide range of shapes, sizes and colors at a lower price.⁷ If a seller calls freshwater pearls Akoya, ask for a lab report that states the environment.