Freshwater pearls are typically white, off-white, or cream in color, while saltwater pearls come in a variety of colors including blue, green, black, and pink. You can also tell the difference by their shape.
There are a few differences between saltwater and freshwater pearls that affect their appearance. Freshwater pearls have a thicker nacre than saltwater pearls, and therefore may have more depth of shimmer to them. However, this thicker nacre also makes them less lustrous or shiny than saltwater pearls.
Cultured Saltwater pearls are more expensive than cultured freshwater pearls because the saltwater oyster only typically only produces one pearl at a time. Freshwater mussels can produce up to 30 pearls at a time. This -- combined with the higher labor costs in Japan -- creates a more expensive pearl.
The colour of saltwater pearls depends largely on the type. Akoya pearls tend to have a blue or grey hue, but they are often bleached white as the trend of wearing pure white pearls still continues to this day. Tahitian pearls are known for their dark, iridescent tones, including black, silver, purple and green.
There are two primary shape categories that all pearls fall into: traditional and baroque. Traditional pearls are round while baroque pearls are virtually anything else. Some prefer baroque pearls for their unique shapes, although traditional pearls are generally more valuable.
The qualities that determine the overall value of a natural or cultured pearl or a piece of pearl jewelry are size, shape, color, luster, surface quality, nacre quality, and—for jewelry with two or more pearls—matching.
Natural Saltwater Pearls come from the Pinctada radiata and Pinctada margaritifera varieties and are native to the Arabian Gulf. These natural pearls are incredibly rare and their value can vary significantly from US$500 to over US$2,000 per pearl.
South Sea pearls are generally much larger than other pearl types and have a unique luster quality – a soft reflection due to the large aragonite platelets that make up the pearl. They also have the thickest average nacre of all cultured pearls. These factors make South Seas both distinctive and valuable.
Naturally colored blue pearls are the rarest pearl colors in the world (with one or two exceptions, which we will get to below). The color has existed in pearls for decades, but only recently have naturally colored blue pearls gained popularity in the modern pearl jewelry markets.
Cultured Freshwater pearls offer a wider range of shapes, with the rarest of them being perfectly round. Because of the Freshwater pearl's lack of internal bead nuclei, these pearls usually have irregular shapes like drops, ovals and baroque.
Freshwater pearls have no core and are made up entirely of mother-of-pearl – so 98% of these stones are not round but oval, buttoned, drop or baroque in shape. Freshwater pearls are cheaper because they are easier to extract, making sea pearls more valued.
The Vinegar Test
A real pearl will dissolve in vinegar or show erosion where the vinegar drop meets its surface. This is because of the chemical reaction between the acid in the vinegar and calcium carbonate, the primary chemical that a real pearl is made of.
Real pearls are cold to the touch. Regardless of the weather, they slowly warm up as you wear them. On the other hand, fake pearls are warm to the touch and don't change temperature. So if you're feeling a cold sensation when you wear your pearls, they're likely real.
Ridges are an inclusion that is unique to Freshwater pearls, quite likely due to their solid-nacre composition.
Each of the colors may be beautiful in their own right, but the most valuable is gold. South Sea pearls are quite large, and they tend to have very thick nacre.
The most valuable and expensive pearls on the market today are the South Sea pearls, which naturally occur in shades of white and gold. How much is a pearl necklace? A classic strand of white pearls can range from $100 (mostly the Freshwater pearls variety) to over $10,000 (Akoya and South Sea pearls).
Not just because of the unique color, size, shape, and place of origin, but also accounting for the fact that these gems are made by living oysters. The price of a pearl now averages between $300-1,500, and there are a few factors to consider when questioning both quality and value.
Extraordinarily rare, naturally beautiful, unmatched in size. Australian South Sea pearls are grown inside the largest and rarest pearl-producing oyster, the Pinctada Maxima. They are highly sought after as the pearls produced are amongst the world's largest and most valuable.
Saltwater Pearl Properties
Creamy white to rose, silvery white, white with greenish hue, yellow, gray, black, black with metallic gray cast, bronze, green, blue. Pearls have body colors as well as overtones. See "Identifying Characteristics" below.
Natural saltwater pearls also like humidity and can get wet. They can be cleaned by slooshing in a salt slurry, which acts as an abrasive to crud struck on the pearl, but does not scratch the pearls.
Pearls with particular brand names will also retain (and even increase) their value over the years; vintage Mikimoto Akoya pearls that still have their original clasp, box and papers to establish provenance are very highly sought after today and continue to fetch premium resale values.
Some of you may be concerned that if their pearls turn yellow, this indicates that they are fake. Contrary to popular belief, imitation pearls very rarely turn yellow due to their composition of plastic and ceramic. Pearls that begin to yellow indicate that they are organic and subject to change.
Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most familiar colors are white and cream (a light yellowish brown). Black, gray, and silver are also fairly common, but the palette of pearl colors extends to every hue.