The decorative glass block includes a bowl-shaped first half and a bowl-shaped second half joined together. The first half and the second half each include a face, a lip surrounding the perimeter of the face, and a wall portion extending outwardly from the lip around the perimeter of the face. Decorations including layers of paint, decals, decoupage glaze, and glitter are provided on at least one of the faces. A hole sized to accommodate a string of lights is provided in one of the faces. The decorative glass block is illuminated using a string of lights inserted into the interior of the decorative glass block through the hole. The decorations enhance the appearance of the decorative glass block and the aesthetic value of light transmitted by the decorative glass block when the decorative glass block is illuminated.