The book I am trying to recall is a novel, historic fiction, about a special stone that appears to many different characters in many different centuries. Each character being from a different era such as ancient Egypt (or was it Rome), southern plantation US … Mostly strong female protagonists who overcome some hurdle or calamity with possession or help of the stone. Not really a magic stone that I recall; no fantasy element to the story -that I recall. But I could be wrong on that point.