I think it is also very important to bring up "The Star of the West", also known as "The Broome Pearl".

This is a pearl that was found by a Japanese diver in 1917. He was working the James Clark, considered by many to be the pearl king of his time. That natural pearl weighed 6.48 grams.

You will also find in a lot of older books, stories upon stories of the pearlers in the early 20th century. Pearlsofjoy is right about the pearl farming, but as early as 1910 Broome was thought to be the Pearl Capital of the world. Divers came from Japan by the hundreds, as did treasure hunters hoping to strike it rich finding that one large pearl.