Do you know that pearls are produced by marine creatures?  

Pearls, one of the most lustrous gems, and nature’s most unique creations, are popular not only between you and me, but are also loved by the Queen of England, who is said to own millions of dollars’ worth custom-made pearls. But do you know how these stones are produced? Well, they are created by molluscs, the underwater invertebrates. Isn’t that simply fascinating? Today, let us dive into the process of how molluscs produce pearls.  

Molluscan magic 
Pearls, as already mentioned above, are formed by marine creatures called molluscs. Molluscs are a diverse group of invertebrates belonging to the family Mollusca and characterised by hard shells that protect their soft, slimy bodies. As some of you might already know from your science books, molluscs which reside in saltwater or freshwater are more likely to produce pearls, say for example pearl oysters or pearl mussels, which are native to the Indian and Pacific Oceans, respectively. But wait, how can an animal without even a backbone, create one of nature’s most beautiful gifts? Well, the story is as intriguing as it can get. 

Pearly processes! 
Simply put, pearls are produced when an irritant, for instance food remains, sand grain, bacteria, or in some cases, even the grains from the mollusc’s own mantle (hard shell covering), get trapped inside the mollusc. Just like humans show signs of suffocation when any foreign particle is stuck inside their throat, similarly, molluscs too start feeling uncomfortable when all these remains stack up. As a result, to protect themselves, they start secreting certain materials around the irritant, a mineral (aragonite) and a protein (conchiolin). Incidentally, these two substances blend together and form a new substance called nacre or mother-of-pearl. Over time, as more and more layers of these substances are deposited, a whole pearl is formed. Fascinating, isn’t it? 

Other factors  
Now that we have already understood how pearls are made, it’s time to explore the other factors involved. For instance, what does the lustre of a pearl depend on? Well, the answer is not as hard as you would think. Pearls with high lustre are created when the aragonite content is more than the conchiolin content and are arranged on top of one another (as if they are overlapping!). In contrast, low lustre pearls are born when the nacre crystals are lesser in amount and are placed perpendicular to the pearls’ growing surface. So, you see, it's all physics and chemistry my friend!