Why Are Pearls Round?

Why Are Pearls Round? Baroque Tahitian Pearls from Spey
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Why are pearls round? It seems intuitive that a pearl is round because of continuous rotation within a mollusk, but until now this theory has remained just that: a theory unable to be demonstrated or confirmed through science. That is, until a groundbreaking study, published in the journal Royal Society Open Science, has demonstrated pearl rotation by mapping the magnetic field variations within the tissues of a living organism. To accomplish this, a specifically engineered magnetic nucleus was inserted into a donor mollusk, initiating the process through which all cultured pearls are formed.

Researchers observed that from at least 40 days from grafting, the irritant or cultured pearl nucleus is continually spun within the mollusk. Famously, the perfect pearl is symmetrically round with a flawless surface. But because pearls are formed inside a living organism, they are heavily dependent on the condition and stability of the mollusk and its environment. The study reveals that even the tiniest disturbance or variation in homeostasis – from a gentle tap on the mollusk’s shell to a complete upheaval of the mollusk’s position and health – can dramatically influence the resulting pearl by leading to less-than-desirable shapes and formations. Organic matter that penetrates the pearl sac, or an infection of the host mollusk, can also inhibit or impair impeccable pearl formation. The study thus explains how baroque and circled pearls get their distinct appearance, with a misshapen body or orbital rings that may reduce the pearl’s value. Surface patterns within the nacre resemble human fingerprints. The slightest variation can cause abstract defects; like a novice potter at the wheel.

It is therefore an obvious conclusion that the health of the mollusk, together with the entire ecosystem in which it resides, are critical factors for pearl formation. The study is yet another example of why the pearling industry is committed to environmental protection and sustainability. Pearls are truly an organic and earth-friendly gem.