Ok, I give up. Where is treasure coast Florida? Your stone looks like nephrite and yes that is jade. Don't take my word though. There is a really nice pic in google images. It does look water polished, but it could be from anywhere, anyone or anytime. It isn't fishtank gravel. Old Digger may be right on about the age because finding jade other than a jewelry store or a tomb in the Yucatan is very rare. It is an interesting find. Congrats...