Sterling Silver Twisted Circle Brooch Pin Stamped 925

Older vintage piece - 3 circles entertwined - stamped STER - there's a little clue on the age. It measures 1 3/8" across - very sturdy piece - strong fold over clasp - works just fine. Could use a rub - did some minor swipe just to make sure it would polish up. Old vintage stock from the late 80's.