This is a stunning mid-century modern Japanese akoya saltwater cultured pearl & black onyx tie bar.

The pearl is 5.50mm round. It has fantastic luster with bright rosy overtones. It is set on a disk of triangular black onyx. Onyx measures 17mm across. 

It is made of solid sterling. Stamped "SILVER" which is an older mark for sterling silver. Measures 1 3/4 inch across. 

All pearls are truly vintage and have only been lightly cleaned. Some light scratching and tiny chips on onyx. Metal could use a polish if desired.