Gregorio is known as the master of San Juan's pottery tradition. He learned his art from his parents and was also a student in the first class of the pottery school in 1978. While other artists were producing traditional utilitarian ware and vases, Gregorio began to look at this as a form of art. He also was one of the first to introduce pre-Columbian designs back into the modern pottery making tradition.
He is truly a master of the Jaguar vessel, which was originally an offeratory piece. This design incorporates the jaguar, a symbol of power and strength, and the fethered serpent, a symbol of intelligence and wisdom.
To produce these authentic looking pieces he uses natural dyes, made of tree sap and earthen minerals, in the tradition of his ancestors. For the black pigment, he gathers sap from local trees and stores the preparation for 30 days to cure it. His works are known for his attention to the finest details. As a result, the National Museum of Culture and History regularly loans him authentic pottery pieces for him to study and replicate.