Ancient Chinese literature refer to pearls as originating in the brain of a dragon and being so lustrous as to be visible from a thousand yards. In Ha Long Bay, the Bay Of Descending Dragons is The Ha Long Bay Pearl Farm.
Until the early 1900’s, natural pearls were accessible to only the rich and famous. It was during this time that Japanese researchers discovered the techniques that could be used to cause oysters to create pearls “on demand.” Oysters create pearls as a defense mechanism. If an irritant, such as sand get inside the oyster shell, they secrete a substance around it which forms a pearl. The Japanese discovered that if you surgically insert an irritant directly into the body of the oyster this will produce a perfect pearl.
Today pearls are affordable and available to all. Cultured pearls share the same properties as natural pearls. The only difference is a little bit of encouragement by man For more info go to http://travelwellflysafe.com/2014/12/02/how-to-make-a-pearl-in-viet-nam/