Virtually impossible, which is why there is no longer a […]
Virtually impossible, which is why there is no longer a global marketplace for natural pearls. The natural pearl oyster beds have become so depleted that in the 1950s, the government of Mexico banned all pearl oyster fishing. All modern pearls are now farmed.
How many natural grains of sand are near-spherical? That’s what pearls form around. They do become more spherical as they grow but many are still misshapen, often badly. Cultured pearl nuclei are always spherical!
Pearls that are unusable for jewellery are ground up to make very good toothpaste - almost pure calcium carbonate.
There's a relative of the Manihiki black-pearl oyster that’s much better eating and contains tiny badly shaped pearls called kishi or keshi. Usually several on the side of your plate after a meal. No real value but tourists like to buy small bag lots to take home and show their friends.