This is an atomic era burst style Japanese akoya saltwater cultured pearl brooch with milgrain.

The pearls are 4.00-5.00mm round. They have great luster with rosy pink overtones. They are a white/cream color.

It features a double row burst leaf design. All the edges have a delicate milgrain detail. It is stamped "SILVER" which is an older mark for sterling. It measures 1 5/8 inches long. From Japan 1930's-1960's.  

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