Yep, this was an amazing find. It's stamped on the back 14k and I took it to a local gold dealer and he said it was definitely 14k gold. I didn't see a designer name. It looks like a custom job. The calf skin leather belt is soft as butter too. It was a lucky pick.
Looks like a "Hickok Buckle" to me. They did make some of gold and some in sterling also. They were a major US belt buckle co. with hundreds of designs. It's possible the co name was omitted to sell as a "Store Brand". I recently found one in the dirt that was monogrammed, it was my grandfathers. Nice Find!