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.