This is a quality mid-century Japanese akoya saltwater cultured pearl tie tac.

The pearl is large and measures 8.50mm round. It has fantastic luster with rosy overtones.

The setting and stem is made of solid 18K yellow gold and is stamped "K18". The back of the tie tac is not gold as is common and appears to be gold plate. From 1950's-1980's Japan. 

All pearls are truly vintage and have only been lightly cleaned.