This is a quality mid-century Japanese akoya saltwater cultured pearl bubble or circle brooch.

The pearls are highly lustrous and measure 7.50-7.75mm and have bright rosy pink overtones. They are a white/pink color. 

It is made of solid sterling silver and has textured details. It is stamped "SILVER" for sterling silver. It measures 1 7/8 inches long. From Japan, 1950's-1980's. 

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