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How does a pearl form?
Quick answer
A pearl works as an oyster's defense: when an irritant slips inside its shell, the oyster coats it in layer after layer of the same smooth material that lines the shell. Over years, these layers build up into a lustrous pearl.
Step by step
- An irritant (like a parasite) gets trapped inside the shell.
- The oyster coats it with nacre, the shiny shell-lining material.
- Thousands of thin layers build up over months and years.
- The layered nacre gives the pearl its glow (iridescence).
- Cultured pearls are made by deliberately inserting a tiny bead.
People also ask
How does an oyster make a pearl?
It defends against an irritant by coating it in many thin layers of nacre, the same smooth material that lines its shell, slowly forming a pearl.
Are natural and cultured pearls different?
Both are real pearls; cultured ones simply start from a bead a farmer inserts, while natural ones begin from a chance irritant.
Why do pearls shimmer?
Light bouncing between the many translucent nacre layers interferes, producing the soft, rainbow-like glow called iridescence.
Part of the guide: Nature & Earth: Living Things and Rocks →