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Beginner’s Guide to the Unique Shapes in Pearls

  • 4 min read

Beginner’s Guide to the Unique Shapes in Pearls

Whether a pearl is cultured or natural, each pearl is truly individual. Starting from the unique colour and lustre of a pearl to the fascinating variety of a pearl’s shape. At Coleman Douglas Pearls, we specialise in choosing unique pearls to accentuate the beauty of each wearer. A pearl’s shape is just one of the many factors involved in this process.

In this post, we will take a closer look at the wide variety of unique shapes one can find in a pearl, exploring the science behind those wonderfully bespoke shapes.

Pearl formation and shape

The shape of a pearl will be largely due to the irritant that originally caused the pearl formation in the first place. In short, when an irritant is detected by a mollusc, it will cover it in epithelial cells, as a way of defending itself, these epithelial cells then deposit layers of nacre. Layer by layer, this eventually forms a pearl, which is naturally influenced by the shape of the irritant that started the process.

A pearl’s shape may also be altered by:

  • An organic substance that attaches itself to the growing pearl. When the substance decomposes, the gases released creates internal blisters between the layers of nacre. This effect produces protuberances in the pearl.
  • A small pearl attaches itself to a larger pearl. The pearl sac surrounds both pearls and continues to secrete layers of nacre.
  • The change in water temperature and salinity can affect the pearl sac, which may tear and form unique marks on the pearl.
  • While growing, a pearl may slide and be impeded by a muscle or organ in the mollusc, an irregular shape will form as the pearl is restricted in its space to grow.
  • Pearls move and rotate while growing. A pointed object might constantly obstruct the pearl and this would produce a ringed or circled pearl, as the movement would have the same effect as moulding on a potter’s wheel.

Different pearl shapes

There are three main groups of pearl shapes – natural pearl shapes, cultured oyster pearl shapes and cultured freshwater pearl shapes.

Shapes in natural pearls

The shapes of a natural pearl can vary owing to the irritant, which caused the formation of the natural pearl in the first place. It could have been a large piece of grit, coral or shell, a worm or larvae, an infection, or any manner of unwelcome guest or intruder against which the mollusc will need to defend itself.

Here are some of the most common shapes of natural pearls:

When natural pearls are found in strands, they tend to be less closely matched in shape and colour tone than their cultured pearl counterparts. This is simply due to the scarcity of natural pearls.

Shapes in cultured oyster pearls

Unless we refer to the half-sphere found in the centre of a Mabe pearl, cultured oyster pearls have a large round portion in their bodies, where the mother of pearl/resin spherical nucleus is located within the pearl. This bead is the irritant that is placed by the pearl technician alongside a strip of nacre-producing epithelial cells into the pearl-bearing oyster to start the cultured pearl formation.

These pearls are termed ‘nucleated’, and can have the following shapes:

Cultured oyster pearls mainly produce just one pearl in their lifetime, proving how rare a cultured pearl can be. The exception being Tahitian pearls which can produce two pearls at the same time.

Shapes in cultured freshwater pearls

Shapes in cultured freshwater pearls can vary from flat and dispersed to round, due to their cultivation process. The process involves placing a piece of mantle containing epithelial cells from a donor mussel into the host mussel, as opposed to the above cultured oyster pearl which uses a mother of pearl or resin bead These cultured freshwater pearls are termed ‘non-nucleated’. The flexibility this cultivation process gives to the eventual formation of the pearl allows us to find literally any shape, including…


The mantle can be cut into a variety of shapes. Once the tissue has triggered the formation of a pearl sac, it produces a pearl. This pearl can be harvested, and the size of it depends on how long the pearl has been left to grow in the mussel. After the first harvest, a mollusc is replaced back into the water where the pearl sac heals and produces another pearl. This can continue for up to three pearl harvests.

This multiple harvest possibility in a mussel is important as in order to produce near perfect round potato shape pearls, freshwater pearls are placed in a tumbling machine to make them perfectly spherical and then re-introduced into a mussel with an existing pearl sac which has just been harvested. This ensures that a freshwater pearl is as round as possible within the constraints of the mollusc pearl producing organism.

Finding your perfect pearls

As touched upon above, pearls come in a wide range of shapes and sizes, not to mention the different qualities and colours.

At Coleman Douglas Pearls, we hand-pick the finest pearls and pearl jewellery to match our customers with designs that are perfect for them. Pearls can be dressed up or down to suit the mood and outfit of their owner. How well this works depends on just how much the pearl jewellery matches your individual style and your personal features that your pearls will be forever complementing – eye colours, face shapes and even your personality.

If you want to find out more, our experts would be happy to discuss your options in a personal consultation. Email or call 0207 373 3369 to arrange an appointment.


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