Came across this brooch today that was sent to me in 1966 or 67 by a US soldier during the Vietnam War. Can anyone tell me what type of pearls they are? I've only noticed a few other "Sakata Pearls" boxes online, and they all have a logo in addition to the lettering, so I wondered if they were real? In my box the satin lining doesn't have a logo, only gold lettering: "SAKATA PEARLS GENUINE CULTURED PEARLS". The back of the brooch is stamped SILVER. Thank you in advance if you can identify. I've attached an image.