vintage natural pearls

by Bill
(Ozark, MO)

There is 167 pearls here on a 42" necklace. I was told by family these are natural pearls from Japan (1960's). The clasp (silver) only has the word "silver" on the bottom. They measure from 5.5 x 6.0mm. Any idea what I may have here? and possible value? Sorry for the poor images...