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Prefer visuals? Explore pearls and understand the differences between natural and cultured pearls with our informative guide. Download now to deepen your appreciation for this exquisite gem!
Have you ever wondered about the fascinating journey of a pearl from the ocean to your jewellery box? Pearls were discovered by chance when early humans opened shells for food. Since then, these lustrous gems have been cherished for centuries, captivating hearts with their timeless beauty. While it’s delightful to admire the allure of pearls, understanding the different types enables you to truly appreciate their elegance and make informed decisions when selecting pearl jewellery.
The classic pearl pendant necklace is a timeless must-have for every woman's jewellery collection. Discover now.
As a Certified Pearl Specialist accredited by the Cultured Pearl Association of America (CPAA), I am passionate about sharing my knowledge of these exquisite gems. In this blog post, I will explain what pearls are and demystify the differences between natural and cultured pearls. Whether you’re a seasoned collector or new to the world of pearls, this guide will enhance your understanding and love for the “Queen of Gems.”
What Are Pearls?
A pearl is a hard and lustrous object formed within a living shelled mollusc. Pearls are primarily composed of nacre, the same material as the smooth inside surface of a mollusc shell. Think of nacre as layers, much like the layers of an onion. These layers are made up of 90% calcium carbonate (CaCO3), deposited in concentric rings, and held together by an organic substance known as conchiolin, which acts like the "glue" binding the layers together.
Anatomy of Molluscs
Now that you know pearls are formed inside living molluscs, let's dive into a simple biology lesson to understand the birthplace of pearls: the anatomy of molluscs. One of the key organs in molluscs that plays a crucial role in pearl formation is the mantle. The mantle covers the main body of the mollusc and contains epithelial cells responsible for producing nacre. Nacre, made of calcium carbonate, is the substance that forms both the shell of the mollusc and the pearl.
Anatomy of a mollusc. (Image Credit: Lauren Cartier, Swiss Gemmological Institute (SSEF))
Natural vs Cultured Pearls
You may have heard of natural and cultured pearls and wondered about the differences between them. Both types of pearls share the same fundamental qualities; the only distinction lies in their formation process. Natural pearls form organically in the wild, entirely without human intervention. In contrast, cultured pearls are nurtured in pearl farms, with careful human assistance guiding their development.
Natural Pearls
The Persian Gulf has been a major source of natural pearls throughout history, with pearl fisheries thriving in the 19th and early 20th centuries. Due to their rarity, natural pearls were luxuries that only kings, queens, and elites could afford, and in many societies, ownership was even restricted by law. However, the high demand led to overfishing, depleting many wild mollusc populations.
Formation of Natural Pearls
Natural pearls form when the mantle of a mollusc is injured, such as when an animal or other foreign object attacks it. This injury causes the mantle tissue to become displaced. When a foreign object enters the mollusc, it can pick up epithelial cells from the mantle as it moves through the mollusc's body. These displaced cells then group together to form a 'pearl sac' around the foreign object.
Cross section of pearl formation. (Image Credit: Walter Schumann, Gemstones of the World (Revised & Expanded Edition))
Think of the pearl sac as a tiny factory. Inside this factory, the epithelial cells continue to do what they are programmed to do: produce nacre. Nacre, the same material that makes up the inside of the mollusc's shell, is gradually deposited over the foreign object. Over time, these layers of nacre build up, forming a natural pearl.
Debunk the Myth: The Grain of Sand Theory
Have you heard of the story that a natural pearl forms when a grain of sand invades a mollusc's soft tissue, and the mollusc coats the grain with shell material to soothe the irritation? This common grain-of-sand theory is just a myth. Let’s debunk it!
Firstly, sand is inactive and does not actively intrude into a mollusc’s body or cause mantle injury. Secondly, pearl formation occurs due to the displacement of mantle cells, not to soothe irritation caused by sand. Extensive tests by gemmological labs on hundreds of thousands of natural pearls have never found a grain of sand inside a natural pearl.
Cultured Pearls
With a dream to adorn the necks of all women worldwide with pearls, Japanese entrepreneur Kokichi Mikimoto pioneered the cultivation of pearls in the late 19th century and successfully created the world's first cultured pearls. This innovation made pearls more affordable, gradually leading to the decline of the natural pearl trade. Today, while a small but vibrant natural pearl trade still exists, more than 90% of pearls on the market are cultured.
Formation of Cultured Pearls
The principles behind pearl culturing are designed to mimic the natural formation process of pearls. Instead of waiting for an accidental displacement of mantle tissue by a foreign object, human intervention guides the process. Producing cultured pearls requires three elements: a host mollusc, the mantle tissue of a donor mollusc, and a bead. The bead, usually made from Mississippi freshwater shells, is carefully shaped into a round form.
To stimulate pearl production, a bead wrapped with a small piece of mantle tissue from the donor mollusc is inserted into the host mollusc. The grafted mantle tissue grows and forms a pearl sac around the bead. The epithelial cells of the mantle tissue, responsible for secreting nacre, begin to deposit regular layers of nacre onto the bead, eventually creating a cultured pearl.
Download our Guide & Explore the Celestial Collection
Thank you for joining me in this exploration of the world of pearls. By delving into the differences between natural and cultured pearls, I hope you've gained a deeper appreciation of this timeless gem. To enhance your understanding, I've created a downloadable guide highlighting these distinctions for your quick and easy reference. Also, don’t forget to explore our Celestial Collection — a stunning range of fine pearl jewellery inspired by celestial bodies.
