Assertion: oyster's pearl | /r/HasProperty | natural
Facets:
Source sentences:
text: One way that jewelers can determine whether a pearl is cultured or natural is to have a gemlab perform an X-ray examination of the pearl.
text: These wild pearls are referred to as natural pearls.
text: Before the days of cultured pearls, black pearls were rare and highly valued for the simple reason that white pearl oysters rarely produced naturally black pearls, and black pearl oysters rarely produced any natural pearls at all.