J. Kašpar was a descendant of pearl artisans from Žírovnice. He perfectly mastered the material, its properties, and the processing method. He was the only one in Slovakia who mastered this type of production. He began cooperating with the ÚĽUV in 1955. His first collection of jewelry, which he made for the ÚĽUV, consisted of brooches in various shapes and sizes. In the years 1977-78, in collaboration with J. Menkynová, he processed several other collections of jewelry. He cut and shaped pearls into round and oval shapes, with surfaces that were smooth but also rich in patterns. He made various sizes of hearts, cylinders, and beads. Each piece was hand-cut and polished. He also contributed to a diverse range of color effects in pearl production. In 1981, he was awarded the qualification of master of folk art production in the field of pearl production, awarded by the Commission for Assessing the Professional Skills of Folk Art Production Workers.