I'm not entirely sure of the origin of this hat, but the beadwork looks similar to some Plains Indian beadwork examples I have researched. Either way, it is extremely skillfull handiwork and appears quite old. I wear a 7 1/8 hat and this fits nicely. The brim measures 4" wide, and the crown is 5" at tallest. The crown also measures 23 around on the exterior.
This is an amazing hat and is unlike anything I have ever come across, grab it while you can! Please message with any questions and I'll do my best to answer.