Coconut pearls
It was first mentioned by the Dutch botanist Rumphius in the 17th century.
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The scientist wrote: "in chemical composition and shape, luster, milky white color this formation of calcium carbonate is similar to pearls, and sometimes surpasses them in hardness"
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How coconut pearls appear is not fully understood. It is believed that such stones appear in coconuts in which all three openings are completely overgrown. They are called blind. The nut embryo cannot grow through the germination opening, dies and hard layers of lime begin to be deposited around it.
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It is the only gemstone in the world of botanical origin.
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Coconut pearls are valued as highly as regular pearls, but they are much rarer.