The Black Opal by Victoria Holt

The Black Opal - Carmel March was found under an azaleas bush when she was an infant. Raised with Dr. Marline’s children her origins were a topic of gossip in the community. When Mrs. Marline is found dead, Mrs. Marline’s brother, Toby, whisks Carmel away on his ship. She lives in Australia for a while and when she comes back to England, she has 3 suitors.