Most Newnan's have the tangs straight out from the base, like Marions. Hillsboro's dip down most of the time. Marion bases are rounded and Newnans are flat like Curt's.Hillsboro base's come down to a short point. They are so valuable when you find one because most of the time the delicate thin bases are missing. But, there are "hybrids of all three styles". And they were made from the crappiest rock to the best, high grade, heat treated coral to be found here. And everyone, paper thin, all percussion flaked except the edge.