Vintage Glow in the Dark Rosary The item in the image is a glow-in-the-dark rosary. It utilizes phosphorescence to absorb and release light. Exposure to light source is needed for it to glow. The amount of glow depends on the light source. Rosaries are often used for prayer and reflection in the Catholic faith. Colors in rosaries can hold symbolic meaning, such as white for purity. The Luminous Mysteries are prayed on Thursdays.