Unknown Pottery Maker

I am a retired person that enjoys going to flea markets, garage sales and thrift shops looking for unusual items that my wife often refers to as junk. I recently found this lovely multi-colored glazed vase. I loved the colors but when I turned it over there was a thick ground glazed bottom similar to how Grueby finished the bottom of there old matte green pottery. It is unmarked and I need help identifying the maker. It is a heavy piece of pottery for it's size and appears to be quite old. Thanks