This is a stunning bright blue Japanese akoya saltwater cultured pearl mid-century modernist brooch.

The pearls are highly lustrous and measure 6.75mm and are a bright blue/gray/green color. They have bright pink overtones. 

It is made of solid sterling silver and has textured details. It is stamped "SILVER" for sterling silver. It measures 1 3/4 inches long. From Japan, 1950's-1980's. 

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