I've been seeing "french pearl" listings on Ebay recently and, being a veteran at this, my best guess is that it's a way of saying it's a fake (i.e. "faux") pearl.
la perle
perle
une perle
perle
PERLE
The french.
they are famous for their black pearl
une perle (fem.)
Marguerite is the French for Margaret which means "Pearl".
Margeaux means "pearl" and is a French form of Margaret.
Nivya is supposed to mean pearl, or leader in French.
Perle noire... No need to thank me