Antique glass, originally made in Bohemia - now Czechoslovakia - made with uranium salts! in the late 1800's to early 1900's. It was the uranium salts that gave these beads their unique coloring. In the early 1900's there were a number of distinctive discoveries and advancements that influenced an obsession with all things 'radioactive'. Later replicas of Vaseline Beads were produced without Uranium (since later science also uncovered the possible harmful effects of radiation), and can be found in multiple hues. The Uranium was replaced with oxides or dyes during the molding process, and manual manipulation used to replicate the fluorescing qualities of Uranium.