There's some people in this outfit that sure have some good eyes. If that oval thing didn't have a cameo in it, there is another option. My dad died in '59. Starting in the 40's he was a rock hound, and I was a pebble puppy. Pop made jewelry out of some of his better finds, and I have a bit of cut and polished petrified wood in a setting just like the one you found, made from a chunk of petrified wood found on the families old Shandon, Calif. homestead. One of my Uncles wondered if it had been a fence post, but that's a different story.