The outstanding glass cups and bowls in the Shōsō-in were imported, but smaller items like beads could be produced in Japan. Much of the glass in the Shōsō-in is leaded glass. This was produced by heating lead and sand together. A small amount of added copper produced green, and a small amount of iron created yellow. The beautiful blues are often of alkali-lime glass, which is made by melting bicarbonate of soda and lime with colored sand. At the time, red glass beads were painted with pigment. See also Alkali-lime glass and Leaded glass.