Eating oyster and bit into pearl?

Many bivalve mollusks can produce pearls. However, the exterior of the pearl will have the same characteristics as the interior of the shell. Pearl oysters have a glossy, iridescent interior, and therefore the pearls they produce have a glossy, iridescent exterior, which is what makes them valuable. Edible oysters have a dull white interior, so any pearl they produce would be dull and white, and not worth anything as a gem.