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What are the Differences Between Natural and Cultured Pearls

Picture of pearl in oyster shell

Different Types Of Pearls

The hunt for natural pearls dates back thousands of years to places like China and the Persian Gulf where divers would swim down to the ocean floor or river bottom to hunt for pearls. Diving for natural pearls was the only means of findings pearls until the late 19th and early 20th centuries where Japanese researchers Mise and Nishikawa developed a technique for creating cultured pearls. Both natural and cultured pearls come from Bivalves which are a family of living shelled molluscs of which there are about 20 pearl producing varieties. Of these only a few are used to produce the varying colour pearls we use today:

  1. Pinctada Margaritifera – Black-Lipped mollusks produce black Tahitian pearls (South Pacific).
  2. Pinctada Maxima – Gold-Lipped or Silver lip mollusks produce champagne or cream pearls (South Sea Pearls).
  3. Pinctada Maxima – White-Lipped mollusks produce silver-white, prink or cream tinged pearls (South Sea Pearls).
  4. Pinctada Fucata – Akoya pearls produce light pink, white or creamy pearls.
  5. Strombus gigas Linnaeus – Pearls from the Queen Conch are very rare and come in shades of cream, gold, grey, brown, orange, red, pink and white pearls.

These molluscs aside from the Conch are made up of two shell halves that open and close for feeding and depending on the variety can be found in salt water or fresh water. Most people think that oysters are the only shellfish that produce pearls, this isn’t the case as both mussels and clams also have the same capability although it much rarer for it to happen.

How Natural Pearls Are Formed

Oysters have a hard protective exterior shell wall but soft delicate bodies on the inside that need protecting. They live in sandy environments and when they get dirt and bits of sand inside their shell they just spit them out. So when you hear that pearls come from a grain of sand this isn’t strictly true. Parasites will sometimes burrow through the oysters outer shell wall and get trapped or die, other times small bits of shell, fish scales or other foreign bodies get caught on the inside shell wall and are unable to be dislodged. To protect its soft body the oyster forms a blister around the irritant that completely encapsulates the foreign body to form a sac. The pearl sack or epithelial cells as it’s also called secretes nacre and conchiolin which coats the irritant to form a pearl. Nacre is made up of crystallized calcium carbonate that is mother of pearl. This smooth thin coating is attached to the irritant by the conchiolin, which is a dark coloured natural organic protein which acts like an adhesive and is only produced to bond the first layer of nacre to the irritant. Throughout the pearls life the sac continuously expands to form concentric micro-layers of nacre around the irritant which gradually increases the size of the pearl in a process that takes years.

How Cultured Pearls Are Formed

Cultured pearls grow in pearl farms some of which are salt water and others freshwater. Unlike natural pearls where the process of an oyster creating a pearl occurs accidentally cultured pearl development is controlled. A nucleus is inserted into the soft tissue of the mollusc, in the case of freshwater pearls a piece of mantle tissue is used and for salt water pearls a mother-of-pearl nucleus is used. The nucleus is usually round in shape as pearls tend to develop into the same shape as the inserted nucleus which acts as a mould. The artificially inserted nucleus which is basically a round bead is nearly as large as a natural pearl; this is because cultured pearls only have a thin layer of nacre, while natural pearls are mostly made of nacre. Once the nucleus is inserted into the oyster the pearl growing process is the same as that of a natural pearl.

Natural vs Cultured Pearls

The process of culturing pearls revolutionised the pearl industry and meant that pearl farmers could control the cultivation of large numbers of consistently high quality pearls. This allows farmers to produce millions of pearls at a time there bye reducing their market value to a level that is affordable to everyone. Natural pearls have become extremely rare because of the huge volumes that were hunted for in the 1800s, which left the world’s natural supply critically low. Add to that the fact that only one in approximately every 10,000 oysters will produce a pearl and of these only a small amount will be of sufficiently high quality. It can take an oyster 5 years to form a tiny 3mm pearl in the wild where as a 7mm cultured pearl can be created from a 6.5mm nucleus in just 3-5 years.

Consistency is another big benefit of cultured pearls, where it’s extremely rare and difficult to find a string of natural pearls that are the exact same shape, colour and size. If one did exist it would be worth hundreds of thousands of pounds where as the same string of cultured pearls would cost just a few hundred pounds. The most desirable shape for pearls is perfectly round which is easily achievable in cultured pearls but finding one is pot luck in natural pearls.

Structure of Cultured Pearl vs Natural Pearl

How Can You Tell The Difference Between Natural And Cultured Pearls?

It’s pretty much impossible to tell the difference between a natural and cultured pearl by just looking at its outer appearance. The only way to make absolute certain whether a pearl is natural or not is to perform an x-ray of the internal structure of the pearl. A natural pearl may show growth lines where concentric layers of nacre have been added. Cultured pearls on the other hand will appear to have a perfectly rounded nucleus that’s surrounded by a halo of conchiolin and finally a thin outer layer. Almost all pearls sold today for jewellery making are cultured pearls and just like natural pearls they come in varying colours, shapes and grades of quality. So when it comes to purchasing pearls you can be sure that they will be of the cultured variety which means that they are real pearls made by oysters and are not artificial as many people think.

Author: Crystal and Glass Beads


  1. I have read that there is a decline in the harvest of cultured pearls believed to be due to pollution so the value of pearls may rise if the number being produced is reduced.

    • Hi Gail you are right pollution has had a big impact on particularly the fresh water pearl production in the US, Japan and China.

  2. Hey Khaled, I really enjoyed your post as it clearly defined the difference between natural and cultured pearls. It’s easy to understand why natural pearls are so much more valuable.

    My wife loves her oysters, I reckon she would have a fit if she found a pearl in one of them lol

  3. It is good to know that hairspray and perfume and other products should never go on pearls. Spray first and pearl later!

  4. I have a pair of cultured pearl earrings.I recently put one of them in for repair which had come away from its gold setting.When I got the earring back it was a totally different colour from its counterpart. When I questoned this, I was told it had been cleaned and polished. Would the dissimilarity be so great in a situation like this? I am curious because I dont think they have given my original earring back

    • Hi Bernadette
      There shouldn’t be a difference in colour to that extent unless the pearls were treated in the first place to colourize them, it would be worth taking them into a jewellery who deals in pearls for their opinion as you paid to have the setting repaired, not the pearls altered. They should be able to advise if the pearls have been treated and if cleaning them should have brought about a change in colour.

  5. I have a string of cultured pearls, that I have had for 20years, I recently took them into a Jewelers to have 2 ” added to the length.There were 58 pearls on the original string. The first thing the Jeweler did was to test them by rubbing his tooth on one of them. ( Yes they are rear I know that, I have the receipt and valuation papers). He said he could get them done . I said I wanted them matched with good quality cultured pearls. They were away for just over two weeks. When I go them back for some reason I tested them in the same way the jeweler did. 2 of the now 69 pearls didn’t feel rough and gritty. In fact they were marked and felt just like plastic. I have taken them back to the same Jeweler but her refused to test them and said her would return them to his supplier. Am I right to think the 2 pearls are not genuine?

    • Hi Sue real pearls are usually gritty which you can feel with your teeth so if you are unhappy you should return them, it doesn’t exactly give you much confidence that they refused to test them in the store, but you can always take them into an independent jewellers once you get them back and ask them.

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